Tutorial 35 |
Squaring a 2-digit number ending in 5
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- Choose a 2-digit number ending in 5.
- Multiply the first digit by the next consecutive number.
- The product is the first two digits: XX _ _.
- The last part of the answer is always 25: _ _ 2 5.
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Example:
- If the number is 35, 3 × 4 = 12 (first digit
times next number). 1 2 _ _
- The last part of the answer is always 25: _ _ 2 5.
- So 35 × 35 = 1225.
See the pattern?
- For 65 × 65, 6 × 7 = 42 (first digit
times next number): 4 2 _ _.
- The last part of the answer is always 25: _ _ 2 5.
- So 65 × 65 = 4225.
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