what is the remainder when 43 ^ 91 is divided by 5 ?
"the units digit of the exponents of 3 cycle in a group of 4 : { 3 , 9 , 7 , 1 } 91 has the form 4 k + 3 so the units digit of 43 ^ 91 is 7 . the remainder when dividing by 5 is 2 . the answer is c ."
subtract(divide(5, const_2), multiply(43, 43))