Arithmetic Operators

Python can do simple calculations using literal values, for example we could type the following into the Shell:

8 + 5

And the Shell would output the answer.

We could put a longer expression into the Shell, and Python would follow the BODMAS rules when calculating the answer.

e.g.

(6 + 3) * 2 - 3 * 3

We can store the result of an expression in a variable which will allow us to use the answer elsewhere in a program.

Try creating a new program with the following code:

print("I will now add the numbers 8 and 5")

answer = 8 + 5

print("The answer is", answer)

When python looks at the second line of code, it always calculates the result of expression first, then it assigns it to the variable.

When you run the program you should get the following output:

We can also use variables in our expressions.

Try creating a new program with the following code:

num1 = 50

num2 = 20

answer = num1 - num2

print(num1, "take", num2, "equals", answer)

Here the expression in num1 - num2.

Python will fetch the value from num1 (50) and subtract the value from num2 (20), calculate the answer then assign it to the variable answer.

When you run the program you should get the following output: