Lua provides common mathematical functions out of the box.
local x = 1.2
print(math.ceil(x))
2
Full list:
math.abs
math.acos
math.asin
math.atan
math.ceil
math.cos
math.deg
math.exp
math.floor
math.fmod
math.huge
math.log
math.max
math.maxinteger
math.min
math.mininteger
math.modf
math.pi
math.rad
math.random
math.randomseed
math.sin
math.sqrt
math.tan
math.tointeger
math.type
math.ult