what is the units digit of ( 147 ^ 25 ) ^ 50 ?
the units digit of the exponents of 7 repeat in a cycle of four , which is { 7,9 , 3,1 } . the number 25 has the form 4 n + 1 so the units digit is 7 inside the bracket . the exponent 50 has the form 4 n + 2 , so the units digit is 9 . the answer is e .
add(add(const_4, const_3), const_2)