Doing break away to subtract what is 13-5?

Both of the numbers 5 and 13 can be broken apart in ways that can help you perform this subtraction.

Break apart 5:
  13 - 5 = 13 - (3 + 2) = (13 - 3) - 2 = 10 - 2 = 8
  13 - 5 = 13 - (10 - 5) = (13 - 10) + 5 = 3 + 5 = 8    (this is how it might be done using a soroban or abacus)

Break apart 13:
  13 - 5 = (5+5+3) - 5 = 5+3 = 8
or
  13 - 5 = (5 + 8) - 5 = 8