For example, if you have 5.3 liters of oil, each barrel can hold 1 liter.

How many oil drums do you need to finish loading?

Obviously, you can't dump that 0.3 liter.

So you have to use six barrels.

Tailing method:

For example, if you have 580 points,

Every 200 points can be redeemed 1 prize.

Then in theory, you can exchange 2.9 prizes.

But there are only two things that can be changed.