In mathematics, there is a function that takes the integer part of the decimal. Writing: []

That is to say, [3.4]=3, [8.9]=8.

(2) If there are decimals, round them off.

{X}=X-[X] is to take the fractional part of x (excluding the integer part). For example {8.9}=8.9-[8.9]=8.9-8=0.9.