Floor brackets look like this: ⌊x⌋
Where x would be the decimal number
⌊4.8⌋ = 4
We ignore the fact that 8 is greater than 4 (basic rounding), so we actually round down, contrary to basic rounding, because we are using floor.
Ceiling brackets look like this: ⌈y⌉
Where y would be the decimal number
⌈6.2⌉ = 7
Again, we ignore what was earlier said.
And that's all there is to it. Simple, aye?