# Erle Robotics Learning Python GitBook Free

## Math operators

With Python you can add, subtract, multiply, divide numbers like this:

• addition = 72 + 23
• subtraction = 108 - 204
• multiplication = 108 * 0.5
• division = 108 / 9
• exponentiation = 2 ** 3
• modulo: Our final operator is modulo. Modulo returns the remainder from a division. So, if you type 3 % 2, it will return 1, because 2 goes into 3 evenly once, with 1 left over.
##### Operators Summary
Operator Meaning
- subtraction
* multiplication
/ division
** power
% remainder of a division
###### Practice 1

We are going to do the following operations:

• Create a integer variable num equal to the sum of two numbers.
• Squar num variable.
• Multiply num from a new variables called num1 equal to the division of two numbers.
>>> # create num variable
...
>>> num = 23 +90
>>> # Notice that a variable can be squared
...
>>> num ** 2
12769
>>> #Create the new variable num1
...
>>> num1= 56/71
>>> print num1
0
>>> #Notice that the division gives integers
... num1=float(56/71)
>>> print num1
0.0
>>> #Now num1 is a decimal (float variable)
...
>>> num*num1
0.0
>>>


###### Practice 2

We are going to follow the steps bellow:

• Create two string variables.
• Sum them.
>>>
>>> #Create two string variables
...
>>> var1 = 'Hello'
>>> var2=' World'
>>> #Sum string variables
...
>>> var1+var2
'Hello World'
>>>


##### Be careful!
• When you divide or multiply a integer by a float variable the result becomes float as well.
• When you divide an integer by another integer, the result is always an integer (rounded down, if needed).
• When you divide a float by an integer, the result is always a float.
• To divide two integers and end up with a float, you must first use float() to convert one of the integers to a float.
• When more than one operator appears in an expression, the order of evaluation depends on the rules of precedence. For mathematical operators, Python follows mathematical convention. You can use brackets ()to reorder the operations.