1. Choose a 2-digit number.
2. Select a number either 3 smaller or 3 larger.
3. Add 1 to the smaller number, then square.
4. Subtract one from the smaller number.
5. Add this to the square.

   Example:

1. If the first number is 78, choose 72 as the second number.
2. The middle number (the average) is 75.
3. Square this middle number: 75 × 75 = 5625. Remember how to square a 2-digit number ending in 5?
4. Subtract 9 from this square: 5625 - 9 = 5616.
5. So 78 × 72 = 5616.

   See the pattern?

1. If the first number is 31, choose 37 as the second number.
2. The middle number (the average) is 34.
3. Square this middle number: 34 × 34 = 1156. Remember how to square a 2-digit number ending in 4?
4. Subtract 9 from this square: 1156 - 9 = 1147.
5. So 31 × 37 = 1147.

   Choose the second number that will give you the easier square, and use your square shortcuts. Practice!