First, divide 591 by 48, because each bus can only hold 48 people, and we don't want the children to die of suffocation (or go insane).
591/48=12.3125
Well, that doesn't look right. After all, we can't have 12.3125 buses (at least, I don't think so).
In this case, yo can't round, because when you do 48*12, you get 576 children that you can take, meaning you'll have to leave some of them.
That just wouldn't work.
Instead, you need another bus, because hey, empty seats are better than tears.
So, you would need 13 buses.
Hope this halos!