1. Choose a number with repeating 9's and a final 4.
2. The square is made up of:
   • one fewer 9 than there are repeating 9's
   • 88
   • the same number of 0's as there are 9's in the square
   • A final 36

   Example:

1. If the number to be squared is 9994:
2. The square has:

   one fewer 9 than the
   repeating 9's:        9 9
88                           8 8
same number of 0's as 9's
   in the square                 0 0
a final 36                           3 6

3. So 9994 × 9994 = 99880036.

   See the pattern?

1. If the number to be squared is 999994:
2. The square has:

   one fewer 9 than the
   repeating 9's:   9 9 9 9
88                          8 8
same number of 0's as 9's
   in the square                0 0 0 0
a final 36                              3 6

3. So 999994 × 999994 = 999988000036.