Multiplying two 2-digit numbers (difference of 4)

Follow the following Steps:

1. Choose a 2-digit number.
2. Select a number either 4 smaller or 4 larger.
3. Find the middle number of the two (the average).
4. Square this middle number.
5. Subtract 4 from this square.

   Example-1:

1. If the first number is 63, choose 67 as the second number.
2. The middle number (the average) is 65.
3. Square this middle number: 65 × 65 = 4225.
4. Subtract 4 from this square: 4225 - 4 = 4221.
5. So 63 × 67 = 4221.

   Example-2:

1. If the first number is 38, choose 42 as the second number.
2. The middle number (the average) is 40.
3. Square this middle number: 40 × 40 = 1600.
4. Subtract 4 from this square: 1600 - 4 = 1596.
5. So 38 × 42 = 1596.