Multiplying two 2-digit numbers (difference of 1)
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- Choose a 2-digit number.
- Select a number either 1 smaller or 1 larger.
- Square the larger number (multiply it by itself).
- Subtract the larger number from the product.
OR
- Square the smaller number (multiply it by itself).
- Add the smaller number to the product. Pick the easier one to square.
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Example:
- If the first number is 76, choose 75 as the second number.
- 75 × 75 = 5625 (square the smaller). Remember how to square a two-digit number ending in 5?
- 5625 + 75 = 5700 (add the smaller).
- So 76 × 75 = 5700.
See the pattern?
- If the first number is 32, choose 31 as the second number.
- 32 × 32 = 1024 (square the larger). Remember how to square a two-digit number ending in 2?
- 1024 - 32 = 992 (subtract the larger).
- So 32 × 31 = 992.
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