Step-by-step explanation: If he is 20% complete, then 20 x 5 is 100. So if we want to get 100%, then we have the multiply. Now he did 16 questions, so we have to multiply 16 five times. 16 x 5
It is because an irrational number cannot be written as a simple fraction ( because there is not a finite number of numbers when written as a decimal ).