when 1 / 20 % of 8,000 is subtracted from 1 / 10 of 8,000 , the difference is
1 / 20 % of 8000 = 4 1 / 10 of 8000 = 800 800 - 2 = 798 ans : d
multiply(inverse(10), multiply(multiply(const_100, const_10), add(const_4, const_4)))