Let's say you and two friends are buying a group ticket to some show. The ticket costs $100. Now try to find a way to pay exactly 1/3 each. Money transfers ten

Let's say you and two friends are buying a group ticket to some show. The ticket costs $100. Now try to find a way to pay exactly 1/3 each. Money transfers tend to involve payments with fixed precisions. For cash, it's often rounded to the smallest available coin, for credit cards, you can add a few more digits, but it will still be fixed point. When you settle a transaction, you typically need to pay exactly the amount defined by the transaction because some system is doing some check that the amount is exactly right. So in my example above, if your friends are paying $33.33 you may have to pay $33.34 to make the transaction go through. When you're writing systems involved in actual money transfers (or accounting) you tend to be better off using fixed point decimal, with predefined precision for each variable involved. Within a calculation, it may be fine to use float, but the number going into ledgers or transactions need to have the predefined precision.