John invests in a bank and gets 10% simple interest.  He invests $1000.  How much money does he have after 3 years?
He gets 1000*.1=$<T>multiply(1000, 0.1)=100.0 a year
So after 3 years, he gets 100*3=$<T>multiply(100, 3)=300
So he has 300+1000=$<T>add(300, 1000)=1300
