Multi-Digit Arithmetic • Explore • Lenny.com

Multiplying Decimals with Regrouping Step-by-Step

This instructional video provides a clear, step-by-step demonstration of how to multiply decimals by whole numbers using the standard vertical algorithm with regrouping. It features three distinct examples that increase in complexity: a one-decimal place number, a two-decimal place number, and a three-decimal place number. The narration uses precise mathematical language, emphasizing place value by explicitly naming units (tenths, hundredths, thousandths) rather than just stating digit manipulation. The key themes explored include the standard multiplication algorithm, understanding place value within decimal operations, and the concept of regrouping (carrying) values across decimal places. The video reinforces the importance of aligning numbers correctly and placing the decimal point accurately in the final product based on the place values being multiplied. For educators, this video serves as an excellent model for explicit instruction or a review tool for students struggling with the procedural steps of decimal multiplication. Its high educational value lies in its script, which narrates the *why* behind the *how* (e.g., explaining that 32 tenths is regrouped into 3 ones and 2 tenths). This supports conceptual understanding alongside procedural fluency, making it suitable for 5th and 6th-grade math classrooms.

MatholiaChannel

2mins 37s

Solving Two-Step Word Problems: Multiplication and Subtraction

This educational video provides a clear, step-by-step demonstration of how to solve a two-step mathematical word problem involving multiplication and subtraction. Through the scenario of a fruit seller named Kevin, the video guides viewers on how to first calculate the total inventory using multiplication (4 crates x 836 apples) and then determine the remaining stock after sales using subtraction. The visual walkthrough specifically highlights the vertical column method for both operations, including regrouping (carrying and borrowing). The video emphasizes the importance of breaking complex problems into manageable parts. It introduces the "bar model" method—a staple of Singapore Math—to visually represent the quantities involved, helping students understand the relationship between the number of crates, items per crate, total items, items sold, and items remaining. This visual approach supports conceptual understanding before moving to abstract calculation. Ideally suited for upper elementary classrooms, this resource helps teachers demonstrate the application of arithmetic skills in real-world contexts. It is particularly useful for lessons on multi-step problem solving, interpreting word problems, and practicing standard algorithms for operations with multi-digit numbers. The clear narration and uncluttered visuals make it an excellent tool for introducing or reviewing these essential math strategies.

MatholiaChannel

1min 49s

Mastering the Difference of Two Squares Factoring Method

This comprehensive math tutorial provides a deep dive into factoring algebraic expressions using the "Difference of Two Squares" method. The video begins by introducing the fundamental formula A² - B² = (A + B)(A - B) and demonstrates how to apply it to simple quadratic expressions. It systematically builds complexity, moving from basic variables to expressions involving coefficients, multiple variables, and higher-degree exponents. The content explores several critical variations of the standard problem type. Key themes include identifying perfect squares, the necessity of factoring out a Greatest Common Factor (GCF) before applying the difference of two squares formula, and handling "repeated factoring" where the result of one step can be factored further. The video also covers advanced scenarios involving binomial expressions treated as single units and expressions containing fractions. For educators, this video serves as an excellent resource for scaffolding instruction in Algebra 1 or 2. It offers a clear procedural breakdown that allows students to master the mechanics of factoring. The progression from simple to complex examples makes it versatile; teachers can assign specific segments for remediation or use the later, more challenging problems for extension activities with advanced learners.

The Organic Chemistry Tutor

19mins 35s

Calculating the Volume of Rectangular Prisms with Examples

This educational video provides a clear, step-by-step tutorial on calculating the volume of rectangular prisms. The video demonstrates the application of the standard volume formula (Volume = Length × Width × Height) through three distinct examples involving different dimensions. Each example is visually represented with a 3D diagram labeled with measurements in centimeters. The content focuses on the core themes of geometry, measurement, and multi-digit multiplication. It reinforces the concept that volume is a three-dimensional measure found by multiplying three spatial dimensions. The video also models the arithmetic process, showing intermediate products when multiplying three numbers sequentially (e.g., first multiplying length by width, then that product by the height). For educators, this video serves as an excellent modeled instruction tool or review resource for 5th and 6th-grade math students. It can be used to introduce the concept of volume calculation or to support students who need repeated exposure to the procedural steps. The consistent format of the problems helps scaffold learning, allowing students to predict the next step in the process and practice their multiplication skills alongside the video.

MatholiaChannel

2mins 6s

Calculating Percent Change with YouTube Subscribers

This educational video provides a clear, step-by-step tutorial on how to calculate percent change using a relatable real-world example involving YouTube subscribers. The narrator, "Mr. J," walks viewers through the standard formula for percent change: subtracting the original value from the new value to find the amount of change, dividing that result by the original value, and finally multiplying by 100 to convert the decimal to a percentage. The video specifically tackles a word problem where a YouTuber's subscriber count increases from 1,572 to 6,390 over a year. It covers essential mathematical procedures including setting up the equation, performing subtraction with large numbers, long division (or decimal calculation), interpreting decimal results, and rounding to the nearest whole percent. The video effectively models how to organize work on paper for clarity. Teachers can use this video to introduce or reinforce the concept of percent increase and decrease. The use of YouTube analytics makes the abstract math concept immediately relevant to digital-native students. It is particularly useful for demonstrating the logic behind percent increases that exceed 100%, helping students understand that a value more than doubling results in a percent increase greater than 100%.

Math with Mr. J

5mins

Finding What Percent One Number Is of Another

This engaging math tutorial breaks down the specific skill of calculating a percentage when given a part and a whole (e.g., "What percent is 20 of 50?"). The video begins by reviewing the relationship between parts, totals, and percentages, establishing that a percentage is simply a ratio out of 100. It categorizes percentage problems into three distinct types—finding a part, finding a percent, and finding a total—and explicitly focuses on the second type for this lesson. The video explores two primary methods for solving these problems. The first method involves using equivalent fractions to scale the denominator to 100, which works well for "friendly" numbers. The second, more universal method involves treating the fraction as a division problem to find a decimal, then converting that decimal to a percentage. The narrator uses humorous skits involving family members giving gifts (travel souvenirs and cookies) to provide concrete word problems that illustrate the math concepts. For educators, this video serves as an excellent bridge between fractions, decimals, and percents. It is particularly useful for helping students transition from simple scaling strategies to the more robust division method required for real-world numbers. The clear visualization of the "Part / Total = Percent" structure helps demystify word problems, while the distinction between the three types of percent questions provides a solid framework for algebraic thinking in middle school math.

mathantics

8mins 28s

How to Multiply Three Integers Using the Associative Property

This video provides a clear, step-by-step tutorial on how to multiply three integers, covering combinations of both positive and negative numbers. Mr. J demonstrates two specific example problems, solving each one using two different methods to prove that the order of operations does not affect the final product in multiplication strings. The video reinforces the fundamental rules of integer multiplication: same signs yield a positive result, while different signs yield a negative result. Key themes include integer operations, the definition of a "product," and the associative property of multiplication. The narrator explicitly defines factors and products, and visually demonstrates how to group numbers differently using parentheses to simplify calculations. The visual aid of a chalkboard with color-coded text helps distinguish between rules and steps, making the process easy to follow for students learning to organize their mathematical thinking. For the classroom, this video is an excellent resource for introducing or reviewing 7th-grade number system standards regarding operations with rational numbers. It effectively models mathematical thinking by showing that problems can be approached in multiple ways. Teachers can use this video to transition students from multiplying two integers to more complex strings of numbers, and to introduce the practical application of the associative property to make mental math strategies more efficient.

Math with Mr. J

5mins 23s

How to Calculate the Original Price from Discounts and Markups

This instructional math video provides a comprehensive tutorial on calculating the original price of items in various real-world scenarios involving discounts and markups. Through a series of clear, step-by-step examples, the narrator demonstrates how to reverse-engineer the starting price when given different variables, such as the discount amount, the sale price, or the markup rate. The video uses specific formulas for each scenario, emphasizing the relationship between percentages, decimals, and whole numbers. The content covers four distinct problem types: finding the original price given a discount amount, finding it given a final sale price, finding it given a markup amount, and finding it given a final selling price including markup. A significant portion of the video is dedicated to the procedural math skills required to solve these problems, specifically converting percentages to decimals and performing long division with decimal movements. The step-by-step visualizations of the division process help demystify the arithmetic that students often struggle with. For educators, this video serves as an excellent resource for 6th and 7th-grade math units on ratios, proportions, and percentage applications. It effectively bridges the gap between abstract formulas and practical application by using shopping and retail examples. Teachers can use this video to introduce the concept of 'working backward' in percent problems or as a remediation tool for students who struggle with the specific mechanics of dividing by decimals.

Sheena Doria

12mins 35s

How to Multiply Fractions and Whole Numbers

This concise mathematics tutorial provides a step-by-step guide on how to multiply proper fractions by whole numbers. The video walks viewers through four distinct practice problems, starting with simple calculations that result in whole numbers and progressing to more complex equations that yield improper fractions. The narrator demonstrates the fundamental technique of rewriting whole numbers as fractions over a denominator of one, allowing for straightforward multiplication across numerators and denominators. Key mathematical themes include fraction multiplication, simplifying fractions, and converting improper fractions into mixed numbers. The video specifically highlights two different mental math strategies for converting improper fractions: standard division with remainders and a decomposition method finding the highest multiple of the denominator. These strategies help students develop number sense beyond simple rote memorization of algorithms. For educators, this video serves as an excellent direct instruction tool or review resource for upper elementary and middle school students. The clear, uncluttered visual presentation focuses entirely on the mathematical steps without distraction, making it ideal for students who need focused procedural support. It connects the operation of multiplication with the skills of simplification and mixed number conversion, offering a comprehensive look at fraction arithmetic in just a few minutes.

The Organic Chemistry Tutor

2mins 41s

Solving Subtraction Word Problems Using Bar Models

This educational video demonstrates how to solve mathematical word problems using bar models and column subtraction with numbers up to 10,000. It presents two distinct real-world scenarios: calculating the profit earned by an art dealer and determining the number of Sunday visitors to a botanical garden based on weekend totals. Each example follows a structured approach of reading the problem, visualizing it with a bar model to identify the unknown value, and performing the necessary calculation. The video explores key mathematical themes including part-whole relationships, the concept of "difference," and the practical application of subtraction in financial and statistical contexts. It specifically reinforces the vertical subtraction algorithm with regrouping (borrowing) across place values. The use of bar models serves as a crucial bridge between the text of the word problem and the abstract arithmetic required to solve it. For educators, this resource is an excellent tool for scaffolding instruction on word problems, which are often a stumbling block for students. The step-by-step visualization helps students understand *why* subtraction is the correct operation before they begin calculating. It is particularly useful for introducing the Singapore Math method of bar modeling or for reviewing subtraction with larger numbers in 3rd and 4th-grade classrooms.

MatholiaChannel

2mins 28s

Calculating What Percent One Number Is of Another

This math tutorial provides a clear, step-by-step demonstration of how to calculate what percentage one number is of another. Using the specific example "30 is what percent of 75?", the video breaks down the process into a three-step strategy: converting the relationship into a fraction, dividing to find a decimal, and finally converting that decimal into a percentage. The narrator, Mr. J, emphasizes the conceptual framework of "part" and "whole" to help students correctly set up the problem. The video covers key mathematical procedures including setting up ratios as fractions, performing long division with decimals, and the mechanics of converting decimals to percentages by moving the decimal point. It specifically addresses the common student struggle of dividing a smaller number by a larger one by demonstrating how to add a decimal point and a zero to the dividend. For educators, this resource serves as an excellent direct instruction tool for introducing percent calculations or as a review for students struggling with the algorithm. The visual presentation uses a blackboard style with color-coded text to distinguish between steps, making it easy for students to follow along. It is particularly useful for bridging the gap between fractions, decimals, and percents in middle school math curriculums.

Math with Mr. J

3mins 26s

Adding 4-Digit Numbers With Regrouping

This educational video provides a step-by-step tutorial on adding 4-digit numbers with regrouping, using the standard vertical column method. It presents two distinct examples: a real-world word problem involving bookstore sales to demonstrate practical application, and a direct calculation problem to reinforce procedural fluency. The video breaks down the addition process by place value—starting from the ones and moving to the thousands—ensuring students understand the sequential nature of the algorithm. A key feature of the video is its visual explanation of regrouping (carrying over). When a column sums to more than 9, the video explicitly demonstrates how to regroup values, such as converting 12 hundreds into 1 thousand and 2 hundreds. This is supported by clear on-screen text, column highlighting, and a character visualization using place value discs to bridge the gap between conceptual understanding and abstract calculation. This resource is highly valuable for introducing or reviewing multi-digit addition in upper elementary classrooms. It supports teachers by providing a clear visual model for algorithms that can sometimes be abstract for students. The step-by-step pacing allows for paused instruction, where teachers can check for understanding at each place value column before proceeding. It effectively addresses the common student error of forgetting to carry numbers or misaligning place values.

MatholiaChannel

3mins 18s

Lessons

Dream School Designer

Neleh Price

Rift Explorers

Neleh Price

Remainder Rumble

nmack

Summit Solvers

cfassel

Summit Solvers

cfassel

Summit Solvers

cfassel

Summit Solvers

cfassel

Soccer Championship Math

Rene Abbene McEvoy

Grid Builder Multiplication

tafranklin

Democracy Data

isaac_daigle

Ten Town Regrouping

Karla Vasquez

Summit Solvers Division

epate

Materials

Dream School Teacher Guide

Neleh Price

Dream School Workbooklet

Neleh Price

Rift Explorers Answer Key

Neleh Price

Rift Explorers Workbook

Neleh Price

Remainder Rumble Teacher Guide

nmack

Remainder Rumble Recording Sheet

nmack

Remainder Rumble Gameboard

nmack

Summit Solvers Quest Cards

cfassel

Summit Solvers Challenge Cards

cfassel

Summit Solvers Recording Sheet

cfassel

Summit Solvers Board Game

cfassel

Summit Solvers Challenge Cards

cfassel

Sequences

Cosmic Base Ten

samantha.davis

Precision Products

vierlingc

Digit Dynasty

Junior Wildlife Detectives

samantha.davis

Summit Math Practice Series

Emily Condon

Movie Math Marathon

stacy maslyn

Prerequisite Pathfinder Pretests

Beth Phillips

Daily Math Gym

alicia accapezzato

ESY Math Mastery

katie_conklin

Party Payday

Jackie Armata

Algorithm Artisans

Alyssa Carabio

Grid Math Scaffolding

cedaniels

Videos

Multiplying Decimals with Regrouping Step-by-Step

Solving Two-Step Word Problems: Multiplication and Subtraction

Mastering the Difference of Two Squares Factoring Method

Calculating the Volume of Rectangular Prisms with Examples

Calculating Percent Change with YouTube Subscribers