Squaring Numbers Ending in 5

  1. Take the digits before the 5 and multiply that number by one more than itself.
  2. Then attach 25 to the end of the result.

Example:

35²
(starts with 3)
3 × 4 = 12
(multiply 3 by one more than itself)

Add 25 → 1225

Another example:

105²
(starts with 10)
10 × 11 = 110
(multiply 10 by one more than itself)

Add 25 → 11025

This pattern works for any number that ends in 5.