Doing math with numbervalues is not working for me?

Just a quick question, right now i'm making a tool that multiples the damage you do by your strength number.

Server Script (The one that does the damage):

-------- wfmp

r = game:service("RunService")
local strength = script.Parent.StrengthValue
local damage = 0.03*strength.Value


local slash_damage = 0.06*strength.Value
local lunge_damage = 0.12*strength.Value

sword = script.Parent.Handle
Tool = script.Parent


function blow(hit)
	local vCharacter = Tool.Parent
	local vPlayer = game.Players:playerFromCharacter(vCharacter)
	local hum = vCharacter:findFirstChild("Humanoid") -- non-nil if tool held by a character
	if hit.Parent:findFirstChild("Humanoid") and vCharacter:findFirstChild("Humanoid") and hit.Parent:findFirstChild("Humanoid") ~= vCharacter:findFirstChild("Humanoid") then
	local humanoid = hit.Parent:findFirstChild("Humanoid")
		tagHumanoid(humanoid, vPlayer)
		humanoid:TakeDamage(damage)
		wait(1)
		untagHumanoid(humanoid)
	end
end


function tagHumanoid(humanoid, player)
	local creator_tag = Instance.new("ObjectValue")
	creator_tag.Value = player
	creator_tag.Name = "creator"
	creator_tag.Parent = humanoid
end

function untagHumanoid(humanoid)
	if humanoid ~= nil then
		local tag = humanoid:findFirstChild("creator")
		if tag ~= nil then
			tag.Parent = nil
		end
	end
end


function attack()
	damage = slash_damage
	local anim = Instance.new("StringValue")
	anim.Name = "toolanim"
	anim.Value = "Slash"
	anim.Parent = Tool
end

function lunge()
	damage = lunge_damage


	local anim = Instance.new("StringValue")
	anim.Name = "toolanim"
	anim.Value = "Lunge"
	anim.Parent = Tool
	swordOut()
	
	wait(.25)
	wait(.25)
	wait(.5)
	swordUp()

	damage = slash_damage
end

function swordUp()
	Tool.Handle.CanCollide = false
	Tool.GripForward = Vector3.new(-1,0,0)
	Tool.GripRight = Vector3.new(0,1,0)
	Tool.GripUp = Vector3.new(0,0,1)
	Tool.Handle.CanCollide = true
end

function swordOut()
	Tool.Handle.CanCollide = false
	Tool.GripForward = Vector3.new(0,0,1)
	Tool.GripRight = Vector3.new(0,-1,0)
	Tool.GripUp = Vector3.new(-1,0,0)
	Tool.Handle.CanCollide = true
end

function swordAcross()
	-- parry
end


Tool.Enabled = true
local last_attack = 0
function onActivated()

	if not Tool.Enabled then
		return
	end

	Tool.Enabled = false

	local character = Tool.Parent;
	local humanoid = character.Humanoid
	if humanoid == nil then
		print("Humanoid not found")
		return 
	end

	t = r.Stepped:wait()

	if (t - last_attack < .2) then
		lunge()
	else
		attack()
	end

	last_attack = t

	--wait(.5)

	Tool.Enabled = true
end


function onEquipped()
end


script.Parent.Activated:connect(onActivated)
script.Parent.Equipped:connect(onEquipped)


connection = sword.Touched:connect(blow)

The "Check" script that checks the strength of the player and puts it into a numbervalue called "StrengthValue":

repeat wait(0.1) until game.Players.LocalPlayer
while true do
	script.Parent.StrengthValue.Value = game.Players.LocalPlayer.leaderstats.Strength.Value
	wait(0.01)
end

If you have anymore question regarding any of this feel free to ask!