Arithmetic

Basic Arithmetic Operators

Calculations are very important in programming. Calculations can be done on the numeric types: ints and floats. Python supports the 4 basic arithmetic operators: +, - , *, /. For example: 3 * 4 returns 12.

Python also supports exponentiation (powers) with the ** operator. For example: 3 ** 2 returns 9.
Note: There is a separate square root function, but don't forget you can use the .5 power to take square roots.

Keep in mind that there is no implied multiplication in programming languages. All multiplication must be written explicitly with a multiplication symbol. This means that 3x must be written 3 * x and 3(x + 4) must be written 3 * (x + 4).

Order of Operations

You may be familiar with order of operations from math. Python will use a similar order to PEMDAS.

1. Parentheses (and other grouping symbols)

2. Exponents

3. Multiplication/Division/Modulus

4. Addition/Subtraction

The order of operations for grouping symbols (), {}, [], <> is inside to outside. Otherwise, the order is left to right.

This includes those used by functions!

Example One: 3 * (4 + (2 + 2))

First the inside parentheses are calculated: 2 + 2
3 * (4 +4)
Then the outside parentheses are calculated: 4 + 4
3 * 8
Then the other operations are done.
24

Example Two: int(input("Input an integer"))

This is not operated left to right! It is operated inside to outside.
First, the input function is called. Then, the string returned by the input is converted to an int!

Absolute Value (and distance)

Absolute value can be used to force values to always be positive.

abs(num)

To find the distance between two numbers (1 dimensional distance) you just subtract and take absolute value.

abs( x - y )

Rounding

To round a float to a certain number of decimal places use:

round( num, places )

For example, round(4.31689, 2) would return 4.32.