*Note: This lesson was written using Python 2.xx. If you are using Python 3.xxx any changes to the code will be annotated under headings: Python 3.xxx

Open up a new Jupyter Notebook. Remember, when working with Jupyter Notebooks, you need to hit Shift+Enter to execute your code.

## Arithmetic Operators

Python Arithmetic Operators are pretty standard. Take note of the division problem in line [9]. 10/7 is not 1, but by default Python only shows integer answers

You can work around it by defining the first number as a float()

### Python 3.xxx

Python 3 handles division differently. To get integer numbers only in division, use //.

10//7 1

10/7 1.4285714285714286

## Arithmetic Operators

- + : Addition
- – : Subtraction
- * : Multiplication
- / : Division
- % : Modulus (returns the remainder of a division problem: 5%2=1)
- ** : Exponent (4**2 = 16)

## Variables

Variables in Python are pretty straight forward. Unlike other programming languages, you do not need to define the variables first. Python dynamically assigns the data type.

Three main rules:

- Variables must start with a letter or _
- Variables are case sensitive
- Avoid using command keywords (print, def, for)

notice lowercase ‘a‘ returns an error

Remember, Jupyter notebooks only return the last command. If you want both variables, use the print command

### Python 3.xxx

In Python 3, print statements require ().

print (A) print (B)

You can perform arithmetic functions on variables

### Python 3.xxx

print (C)

And of course, variables can hold strings as well as numbers

### Python 3.xxx

print (E) print (F)