Can someone help with this math problem I have with my build system?

    print(math.floor(Mouse.Hit.X / GridSize) * GridSize)
    print(math.floor(Mouse.Hit.X))

Let's say that mouse X is 50 and gridsize is 2. That means that the first one will do 50/2 = 25 * 2 = 50 Bottom one will be 50.

Same answer, yet, when I made a snap building system, it gives different results.

FULL SCRIPT:

local Player = game.Players.LocalPlayer
local Mouse = Player:GetMouse()


local PosX
local PosY
local PosZ

local Model = game.ReplicatedStorage.Crate:Clone()
Model.Parent = workspace

local GridSize = 5



local function snap()
    PosX = math.floor(Mouse.Hit.X / GridSize) * GridSize
    PosY = Model.PrimaryPart.Position.Y
    PosZ = math.floor(Mouse.Hit.Z / GridSize) * GridSize
end

local function Movement()
    --Mouse.TargetFilter = Model

    snap()

    Model:SetPrimaryPartCFrame(CFrame.new(PosX, PosY, PosZ))
end

Mouse.Move:Connect(Movement)