Placeholder Power Anchor Chart
PLACEHOLDER POWER
2-Digit × 2-Digit Multiplication • Standard Algorithm
Classroom Anchor Chart
The Standard Algorithm
2
| |
| | • | 3 | 7 |
| × | | 2 | 4 |
| | 1 | 4 | 8 |
| | 7 | 4 |
0
|
| + | 8 | 8 | 8 |
The "Why" Behind The Magic
Standard algorithm is just a fast way to do partial products and add them up:
37 × 4 ones = 148
37 × 20 tens = 740
Combine Sum = 888
Step 1
The Ones Attack
37 × 4
Multiply 37 by the ones digit of the bottom number (4).
- 7 × 4 = 28 → Write down 8, carry the 2 to the Tens column.
- 3 × 4 = 12 → Add the carried 2 to get 14. Write it down!
Step 2
Deploy the Placeholder
Magic Zero
Before multiplying the Tens, place a Magic Zero (0) in the ones column of your second work row.
CRITICAL: Since you are multiplying by 20 (not 2), this placeholder keeps your columns perfectly aligned!
Step 3
The Tens Turn
37 × 2
Multiply 37 by the tens digit of the bottom number (2).
- Cross out the old carried 2 so you don't use it again!
- 7 × 2 = 14 → Write down 4, carry the 1 to the Tens column.
- 3 × 2 = 6 → Add the carried 1 to get 7. Write it down!
Step 4
Combine Forces
148 + 740
Add both partial products together vertically to find your final answer!
148 + 740 = 888
Standard Algorithm Quick Checklist
The Magic Zero?
Did I put a placeholder in the ones column of Row 2?
Clean Carries?
Did I add my carried values and cross out old ones?
Perfect Align?
Are all columns (Th, H, T, O) lined up perfectly?
