Calculator

numbers = {}

function checkNumber(xmin,ymin,xmax,ymax,output)
    local event, button, x, y = os.pullEvent()
    if event == "mouse_click" and button == 1 then
        if x >= xmin and x <= xmax and y >= ymin and y <= ymax then
            table.insert(numbers, output)
        end
    end
end

function keypad()
    checkNumber(3,13,5,13,1)
    checkNumber(8,13,10,13,2)
    checkNumber(13,13,14,13,3)
    checkNumber(3,11,5,11,4)
    checkNumber(8,11,10,11,5)
    checkNumber(13,11,14,11,6)
    checkNumber(3,9,5,9,7)
    checkNumber(8,9,10,9,8)
    checkNumber(13,9,14,9,9)
    checkNumber(3,15,10,15,0)
end

function displayScreen()
    print("+------------------------+")
    print("|+----------------------+|")
    print("||                      ||")
    print("|+---++---++--++---++---+|")
    print("||MC ||MR ||MS||M+ ||M- ||")
    print("|+---++---++--++---++---+|")
    print("||<--||CE ||C ||+/-||SRT||")
    print("|+---++---++--++---++---+|")
    print("|| 7 || 8 ||9 || / || % ||")
    print("|+---++---++--++---++---+|")
    print("|| 4 || 5 ||6 || * ||1/X||")
    print("|+---++---++--++---++---+|")
    print("|| 1 || 2 ||3 || - ||   ||")
    print("|+---++---++--++---+| = ||")
    print("||   0    ||. || + ||   ||")
    print("|+---++---++--++---++---+|")
    print("+------------------------+")
    print("")
    print("")
end
displayScreen()
while true do
    keypad()
    term.setCursorPos(3,3)
    term.write(numbers[1])
end