find the simple interest on $ 10000 at 4 % per annum for 12 months ?
"p = $ 10000 r = 4 % t = 12 / 12 years = 1 year s . i . = p * r * t / 100 = 10000 * 4 * 1 / 100 = $ 400 answer is a"
multiply(10000, divide(4, const_100))