Maths and variables

Fix the program below by identifying the issues in it:

Print(Please enter your name")
Print("Hello there " Get_input()

Fix this program:

Fix the program below by identifying the issues in it:

print("Please enter your name")
print("Hello there " + input())

Fix this program:

How to use maths in Python
How to use variables in Python
To further our skills with input and output in Python

Be able to use maths in Python
Be able to explain why we use variables
Be able to write variables in Python
Be able to develop your own calculator program

Reminder!

In the last lesson we looked at getting an input from the user.
Remember that if we want Python to treat that input as a number we need to use int.

x = 5
y = int(input("Please enter y"))

z = x * y
print(z)

Maths in Python

Maths in Python is very similar to how it is done in actual maths. For example, in maths you write 5 + 5 and in Python we just write 5 + 5.
Here is a table of the different maths symbols we can use in Python:

Maths symbol	Python symbol	Purpose
+	+	Addition
-	-	Subtraction
×	*	Multiplication
÷	/	Division
%	%	Modulus (get the remainder)

Maths in Python

print(5 + 5)
print(5 - 5)
print(5 * 5)
print(5 / 5)

print(5 + int(input()))

Maths icons created by Eucalyp - Flaticon

Algebra

y = 10

z = 2

x = y × z

What is x equal to?

Getting the remainder

When performing a division of two numbers, e.g. x and y, the number you get back from this is called the quotient.
Thinking about a group of five people. If exactly half of them go on holiday in at the one time, how many of them go on holiday each time?
- 2 or 3
- Or would it be 2.5 people?
We cannot have a half person, so instead we have 2 remainder 1.
In Python, we use the % symbol to get the remainder of a division sum:

print(5 % 2)

Calculate the quotient and remainder for each of the following:

13 ÷ 5

9 ÷ 7

81 ÷ 21

Example

2 r 3

1 r 2

3 r 18

7 ÷ 3

Calculate the quotient and remainder for

3 × 2 = 6

7 - 6 = 1

2 r 1

List the multiples of 3 until they are bigger than 7 and stop.

Remainder in Python

print(9 / 4)
print(9 % 4)

Mathematical symbols in Python

Variables

Python uses something called variables to store data in the same way we use x, y and z in algebra.
Variables are like a box that contains a single value:

Variables in Python

Python variables

y = 10
z = int(input("Please enter a number"))

x = y * z

print(x)

Why do we use variables?

Variables store values in main memory so we can get the value from them later.
If we take a user’s input and we want to add 5 to it and then print it, we would get a long statement.
Variables make code easier to read.

print(int(input()) + 5)

user_input = int(input())
x = user_input + 5
print(x)

Even and odd numbers

Any number when divided by 2 which gives a remainder of 0 is an even number.
Any number when divided by 2 which gives a remainder of 1 is an odd number.

To use this, we can write an if statement to check this:

number = 7

if number % 2 == 0:
  print("This is an even number")

Check your understanding

x = 5
y = x
x = 10
print(y)

What will this program print?

z = 10
x = 10
y = 3
z = y * y
print(z)

Check your understanding

x = 5
y = x
x = 10
print(y)

What will this program print?

z = 10
x = 10
y = 3
z = y * y
print(z)

- Create a program to take a person’s name in and store it in a variable
- Print the user’s name on to the screen
Challenge
- Create a program that takes in two numbers and stores them in variables
- Create a third variable that stores the result of these two numbers being added together
- Print the third variable to the screen
Complete all the tasks on the worksheet.

Task

Click here for the worksheet

Grade yourself

I can use maths in Python to add, subtract, multiply and divide several numbers

I can write a program using variables that stores the user's input in a variable

I can write a simple calculator program that takes two numbers and performs an operation on them

Presentation Overview

Maths and variables

00:20 | 24-01-2026

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Use two's complement

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