Number and string operations

Numbers

References: - https://docs.python.org/3/tutorial/introduction.html#numbers - https://docs.python.org/3/tutorial/introduction.html#using-python-as-a-calculator

Arithmetic operations

Addition

>>> 2 + 12
14

Subtraction

>>> 2 - 12
-10

Multiplication

>>> 2 * 4
8

Division, with a float as the answer

The division operator of / returns a float (decimal) number by default:

Whole number division

To divide 2 numbers and only get a whole number, use a double forward-slash: //

>>> 11 // 7
1

Get the remainder of a division operation

This is also known as the modulo operation, which uses the percent sign as its operator:

>>> 7 % 5
2

Built-in functions for numbers

Round a fractional number to nearest integer

Use round

>>> round(9.99)
10

Round a fractional number to the nearest n decimal places

Use round and pass in a number as second argument indicating the number of decimal places to round to.

>>> round(8.23593, 1)
8.2

Convert an integer to a float

Use the float() class method and pass in an integer as an argument. The returned value will an equivalent number, but with a data type of float:

>>> float(42)
42.0
>>> type(float(42))
float

Convert a float to an int; or, truncate a float to a whole number

Use the int() class function to truncate a float – note that the result will be an integer, but not what you would get if you used the round function:

>>> int(4.999)
4

Strings

Concatenate 2 strings together

Also known as “combine 2 strings”. The plus sign can be used for concatenation: