Is there a way in Roblox Studio to assign something a random number?

This is the best I can do with the little information you game me. For it to work the object must be named "small shack" and be parented to the folder containing the models.

local c1 = 1 -- Folder Count
local c2 = 1 -- Replicated Storage Count
local folder1= script.Parent -- The Folder containing Models
local folder2 = game:GetService("ReplicatedStorage").FolderNameHere -- The Replicated Storage folder, replace FolderNameHere With correct folder

for _,child in ipairs(folder1) do -- Loop through the folder containing models
    if child.Name == "small shack" then -- Detect and check model name
        child.Name = "small shack" .. tostring(c1 -- Rename the model
        c1 = c1 + 1 -- Increase the number by 1 for next time
    end
end
for _,child in ipairs(folder2) do -- Loop through the Replicated Storage folder
    if child.Name == "small shack" then -- Detect and check model name
        child.Name = "small shack" .. tostring(c2)-- Rename the model
        c2= c2+ 1 -- Increase the number by 1 for next time
    end
end

folder1.ChildAdded:connect(function(child) -- See if child added to folder1
    if child.Name = "small shack" then -- Detect and check model name
        child.Name = "small shack" .. tostring(c1) -- Rename model
        c1 = c1 + 1 -- Increase the number by 1 for next time
    end
end)
folder2.ChildAdded:connect(function(child) -- See if child added to folder2
    if child.Name = "small shack" then -- Detect and check model name
        child.Name = "small shack" .. tostring(c2) -- Rename Model
        c2= c2+ 1 -- Increase the number by 1 for next time
    end
end)

Next time please include more information. I hope this fixed your problem!

You're not looking for a random number but more so a unique number.

Here's a small example to illustrate the idea. Here I use a string table and string.find(string, searchString). If the searchString cannot be found it will return nil. You'll also need to use tostring() as shown below since you'll be using objects and not strings.

You could also have a continuous counter stored after each iteration and saved with DataStore but that may be more of a hassle.

local numOfShacks = 0
local SMALL_SHACK = "Small_Shack"
local shacks = {"Small_Shack1","Small_Shack2","Small_Shack3","Small_Shack4","Small_Shack5"}

local function CountShack()
    numOfShacks = 0
    for _,shack in pairs(shacks) do
        if string.find(tostring(shack), SMALL_SHACK) then
            print(shack)
            numOfShacks = numOfShacks + 1
        end
    end
end

local function MakeNewShack()
    local newShackName = SMALL_SHACK .. numOfShacks + 1

    table.insert(shacks,newShackName)
end

CountShack()
print(numOfShacks) --5
MakeNewShack()
CountShack()
print(numOfShacks) --6