Complete round function

-- superscript generator (for numbers)

function to_super(x)
    local function number_to_super(x)
        local y = tonumber(x)
        if y ~= nil then
            local tab = {"¹","²","³","⁴","⁵","⁶","⁷","⁸","⁹"}
            if tab[y] ~= nil then
                return tab[y]
            else
                return "⁰"
            end
        end
    end
    local y = tostring(x)
    local str = ""
    for i=1,#y do
        str = str..number_to_super(string.sub(y,i,i))
    end
    return str
end

-- im going to make a complete rounding function

function round(number,deci)
    local num = tostring(number)
    local num2 = ""
    local num3 = ""
    local num4
    local savevar1 = ""
    for i=1,#num do
        if string.sub(num,i,i+1):lower() == "e+" then
            savevar1 = string.sub(num,i+2)
            num2 = string.sub(num,1,i-1)
            break
        end
    end
    if num2 ~= "" then num = num2 end
    for i=1,#num do
        if string.sub(num,i,i) == "." then
            num3 = tonumber(string.sub(num,deci+i+1,deci+i+1))
            num4 = tonumber(string.sub(num,deci+i,deci+i))
            if num3 == "" or num3 == nil then break end
            if num3 >= 5 then
                num = string.sub(num,1,i-1+deci)..tostring(num4+1)
            else
                num = string.sub(num,1,i-1+deci)..tostring(num4)
            end
        end
    end
    if savevar1 ~= "" then
        num = num.." * 10"..to_super(savevar1)
    end
    return num
end

print(round((8213.2791),2));print(round((9.32874723 * 17^39),2))