Using Python as a calculator¶
Calculating 2+2¶
One of the simplest uses of Python is as a simple calculator.
This also introduces us to the idea of working with numbers which is a key part of using Python for scientific applications.
Open a new Notebook and enter into a code cell
2+2
If you run this cell you should get something that looks like the screenshot below.
The cell has run (indicated by the number 1 to the left of the cell), and the “code” has produced a result, which is printed below the cell. Beneath that you get a new, empty cell for your next piece of code.
Within this course book cells that have been run are rendered as follows:
2+2
4
You can add space between the numbers to make things easier to read:
2 + 2
4
Or wrap the expression in brackets:
(2 + 2)
4
And still get the same result.
Simple arithmetic¶
You are not limited to adding numbers. Try entering the following expressions into code cells and executing them (running the cells.):
subtraction:
3 - 1
multiplication:
4 * 2
powers (e.g. 42)
4 ** 2
division
6 / 2
Integers and Floats¶
Notice that the last example gives 3.0 and not 3 as the result. Python distinguishes between integers (also called ints) and floating point numbers (also called floats):
Integers: A number without a decimal point: e.g. 1, 2, 100, 2100.
Floats: A number with a decimal point. e.g. 3.14159, 12.0107, 8.3144 (you might recognise these).
Arithmetic also works with floats:
2.0 + 2.0
4.0 * 2.0
4.0 ** 2.0
6.0 / 2.0
And with mixtures of integers and floats
2 + 2.0
4 * 2.0
4.0 ** 2
6 / 2.0
Notice how these last examples always output a float.
floats can also be written without any numbers after the decimal point, e.g.
42.
is the same as 42.0.
You can do integer division (also called floor division ) using //:
6 // 2
Integer division rounds down:
7 // 2
You can calculate the remainder of integer division using the % symbol (called the modulo operator).
7 % 2
8 % 2
Brackets can be used to specify the order of operations in more complicated expressions, according to the usual mathematical rules:
(2 + 3) * 4
2 + (3 * 4)
We will return to mathematical expressions in Python in more detail later in the course.