Area, Circumference,AA, CC calculator (Lua)

-- I got lazy in math so I made a calculator to literally solve all of my problems

Amount_of_decimals = 2

Radius = 0
Diameter = 3



function removedec(number)
    num = tostring(number)
    for i=1,#num do
        if string.sub(num,i,i) == "." and string.sub(num,i+1,i+1) == "0" and string.sub(num,i+2,i+2) == "" then
            num = tonumber(string.sub(num,1,i-1))
            break
        end
    end
    return tonumber(num)
end


if Radius == 0 then
    Radius = removedec(Diameter/2)
elseif Diameter == 0 then
    Diameter = Radius*2
end

local g = "0."

for i=1,Amount_of_decimals do
    if i ~= Amount_of_decimals then
        g = g.."0"
    else
        g = g.."1"
    end
end
g=tonumber(g)
ekk = g

EA = removedec(Radius^2)
AA = removedec(EA*math.pi)
AS = tostring(AA)
for i=1,string.len(AA) do
    if string.sub(AA,i,i) == "." then
        if tonumber(string.sub(AA,i+Amount_of_decimals+1,i+Amount_of_decimals+1)) >= 5 then
           AA = tonumber(string.sub(AA,1,i+Amount_of_decimals))
           AA = AA+ekk
        else
            AA = tonumber(string.sub(AA,1,i+Amount_of_decimals))
        end
    end
end
EC = Diameter
CC = removedec(EC*math.pi)
for i=1,string.len(CC) do
    if string.sub(CC,i,i) == "." then
        if tonumber(string.sub(CC,i+Amount_of_decimals+1,i+Amount_of_decimals+1)) >= 5 then
           CC = tonumber(string.sub(CC,1,i+Amount_of_decimals))
           CC = CC+ekk
        else
            CC = tonumber(string.sub(CC,1,i+Amount_of_decimals))
        end
    end
end

print("Radius: "..Radius.."\nDiameter: "..Diameter.."\nExact Area: "..EA.."\nDec Area: "..AA.."\nExact Circumference: "..EC.."\nDec Circumference: "..CC)