Prime Calculator

function scanNumber(n)
    for i = 2, math.floor(n/2) + 1 do
        if n % i == 0 then
            return false
        end
    end
    return true
end

function getCurrentNumber()
    local num = 3
    nFile = fs.open("primeIndex", "r")
    if nFile then
        num = tonumber(nFile.readAll())
    end
    nFile.close()
    return num
end

function saveCurrentNumber(num)
    nFile = fs.open("primeIndex", "w")
    nFile.write(num)
    nFile.close()
end

function addPrime(prime)
    pFile = fs.open("primeList", "a")
    pFile.writeLine(prime)
    pFile.close()
end

local number = getCurrentNumber()
while true do
    saveCurrentNumber()
    if scanNumber(number) then
        addPrime(number)
        print(number)
    end
    number = number + 1
    if number % 50 == 0 then
        sleep(.01)
    end
end