Multiplying a 2-digit number by
101
- Select a 2-digit number .
- Write it twice!
Examples:
- 47 x 101 = 4747.
- 38 x 101 = 3838.
- 96 x 101 = 9696.
Multiplying a 3-digit number by
101
- Select a 3-digit number .
- The sum of the first and third digits will be the middle digit: _ _ X _ _.
- The first two digits plus the carry will be the first digits: X X _ _ _.
- The last two digits of the number will be the last digits: _ _ _ X X.
Example:
- The number chosen is 318.
- 3 + 8 = 11 (sum of first and third digits):
_ _ 1 _ _ (keep carry, 1)
- 31 + 1 = 32 (first two digits plus carry):
3 2 _ _ _.
- The last two digits are the same:
_ _ _ 1 8.
- So 318 x 101 = 32118.
See the pattern?
- If the number chosen is 728:
- 7 + 8 = 15 (sum of first and third digits):
_ _ 5 _ _ (keep carry, 1)
- 72 + 1 = 73 (first two digits plus carry):
7 3 _ _ _.
- The last two digits are the same:
_ _ _ 2 8.
- So 728 x 101 = 73528.
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