Subtracting the squares of two numbers

1. Select a 2-digit number and then choose a number two larger or two smaller.
2. Multiply the middle number by 4.

   Example:

1. If the the first number selected is 31:
2. Choose 29.
3. Multiply the number between them by 4: 4 x 30 = 120
4. So (31)(31) - (29)(29) = 120.

   See the pattern?

1. If the the first number selected is 63:
2. Choose 61.
3. Multiply the number between them by 4: 4 x 62 = 248
4. So 63^2 - 61^2 = 248.

   One more:

1. If the the first number selected is 73:
2. Choose 75.
3. Multiply the number between them by 4: 4 x 74 = 296
4. So (75x75) - (73x73) = 296.