How do I make a TextBox number rise by a number in another TextBox?

Ever heard of make it rain? Try to remember this concept while helping me. I am trying to make a Pickles Per Second like 'Money per second' Here is what I have tried so far.

P = script.Parent.Parent.Parent.Pickles.Text
L = script.Parent.Value
N = 0

while true do
	N = P + L
	wait(1)
	local str = script.Parent.Parent.Parent.PPS.Text;
	local lel = tonumber(str:match("^%d+"));

	script.Parent.Parent.Parent.Pickles.Text = N .. " Pickles"

end

Go with what TheAlphaStigma said and use

 N = P.tonumber + L

Alpha said Your problem is that you are only saving 'P' as a String, not a Number Value! Even so, on line 6, you'll still be attempting to compare a String to a Number Value. Consider using 'tonumber'?

ALL CREDIT GOES TO ALPHA!