Lua help UnitDebuff

[Lane]

I'm trying to calculate the time remaining for a specific debuff. I'm not getting any errors but I think my lack of lua Math and Rounding is causing a nonsensical return.

Given:

local function getSpellTime(spell)
	local name, _, _, _, _, dur, exp, caster = UnitDebuff("target", spell)
	if name ~= nil and caster == "player" and name == spell then
		return exp - GetTime();
	end
end

My return value is usually something like 2... or 4...

Any idea what I need to get whole second times?