Playing with numbers
- Any two-digit number ab, made of digits a and b, can be written in general form as ab = 10a + b whereas the number ba can be written as ba = 10b + a.
For example, 45 = 4 × 10 + 5 and 54 = 5 × 10 + 4
- A three-digit number abc, made of digits, a, b, and c, can be written in general form as abc = 100a + 10b + c.
For example, 456 = 4 × 100 + 5 × 10 + 6
- The sum of a two-digit number and the number formed by reversing the digits is always a multiple of 11.
For example, 28 + 82 = 110 = 11 × 10 is a multiple of 11.
- The difference between a two-d…
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