Problem: if n is the greatest positive integer for which 2 ^ n is a factor of 8 ! , then n = ?
Rationale: "8 ! = 40320 e . 2 ^ 10 = 512 ( 40320 / 512 ) - this is not a factor of 8 ! d . 2 ^ 8 = 256 ( 40320 / 256 ) - this is not a factor of 8 ! c . 2 ^ 6 = 64 ( 720 / 64 ) - this is a factor of 8 ! c is answer"
annotated_formula: subtract(divide(8, const_2), const_1)