math.modf

local integer, fraction = math.modf(
    value
)

Type	Name	Description
`number`	value	Number to split into integer and fractional parts

Type	Name	Description
`int`	integer	Integer part of value
`number`	fraction	Fractional part of value (same sign as value)

Split a positive float

local integer, fraction = math.modf(4.75)

engine.print("info", integer, fraction) -- 4  0.75

Split a negative float

local integer, fraction = math.modf(-3.25)

engine.print("info", integer, fraction) -- -3  -0.25

Split an exact integer

local integer, fraction = math.modf(10.0)

engine.print("info", integer, fraction) -- 10  0.0

Get only the integer part

local integer = math.modf(9.99)

engine.print("info", integer) -- 9

Get only the fractional part

local _, fraction = math.modf(9.99)

engine.print("info", fraction) -- 0.99

Separate seconds and milliseconds

local elapsed = 3.456
local secs, ms = math.modf(elapsed)

engine.print("info", secs, math.floor(ms * 1000)) -- 3  456

Check if a number is a whole integer

local n = 5.0
local _, fraction = math.modf(n)

if fraction == 0 then
    engine.print("info", "Whole number")
end