Write any three digit number to meet the following requirements: 1. The number of hundred is larger than that of one 2. Exchange hundreds and ones, and subtract decimals from large numbers 3. Exchange the hundreds and individual digits of the difference, and add with the difference between the large number and the decimal It turns out to be 1089 every time. Why?

For example, s is XYZ (x is a hundred, y is a ten, Z is a single digit)
S=X*100+Y*10+Z
After reversing the number of hundred and each digit, S1 = Z * 100 + y * 10 + X
1. Known x = Z + 2
2. So s-S1 = (x * 100 + y * 10 + Z) - (Z * 100 + y * 10 + x) = 99x-99z = 99 * (x-z) = 99 * 2 = 198
3.198+891=1089
So it turns out

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