John has taken 10 pictures every day for the past 3 years.  He saves them in raw format so each memory card can store 50 images.  Each memory card costs $60.  How much does he spend on memory cards?
He takes pictures for 3*365=<T>multiply(3, 365)=1095 days
So he takes 10*1095=<T>multiply(10, 1095)=10950 pictures
That means he needs 10950/50=<T>divide(10950, 50)=219.0 memory cards
So he spends 219*60=$<T>multiply(219, 60)=13140 on memory cards
