Using arithmetic operations in Python
problem
You would like to perform arithmetic operations in Python. That includes simple mathematics like addition +, subtraction -, division /, and multiplication *. In this post we will see simple examples on how to use these operators.
SOLUTION
Same with mathematics we have 4 operators for the 4 classic actions:
- Add
- Subtract
- Divide
- Multiply
Addition
Open the Python interpreter and type a simple addition
3 + 5
Hit enter and the answer will appear below
The + operator is binary meaning it takes two arguments, in this case 3 and 5 and adds them together. It can take variables also or the result of function and add it.
For example:
x = 10
x + 8
Or, a variable plus itself (or other variable)
The + operator can also be used as a unary operator meaning taking only 1 parameter. In this case, it makes the number positive.
For example:
+9
Note: No space between the + symbol and the number.
Also, it can be used on a variable:
+x
This way you put a positive sign in front of the number, same with mathematics.
Note: Numbers are positive by default, so in this case it won’t change anything.
Adding two (positive) numbers together:
+60 + +9
Subtraction
The – operator is used for subtraction and is also a binary operator.
It takes 2 parameters and subtracts the one to the right from the one to the left.
In this case, let’s see how to subtract 5 from 8.
8 - 5
Simple, like in mathematics.
As we saw in the addition, the – operator can also be used as a unary operator to negate the number.
For example, to turn a number into its negative representation, we can do the following:
-7
The number 7 is negative now, -7
Note: There is no space between the – symbol and the number.
It can be applied on variables too. For example:
x = 10
-x
If we have a negative number already and we negate it again, we get its positive representation. For example:
--5
Or by using parentheses to make it look clearer:
-(-5)
Having a negative number stored in a variable:
n = -6
-n
If we negate it, it turns positive.
We can also subtract negative and positive numbers:
-5 - 7
We have -5 and 7
Let’s subtract 7 (positive) from -5 (negative)
Answer: -12. The same with mathematics, the 7 will turn -7 and we have -5-7 = -12
Multiplication
To multiply numbers we use the *. Again as a binary operator, we use two numbers with the sign in between them and it will multiply them.
For example, let’s multiply 3 and 5
3 * 5
Simple, like in mathematics.
Let’s multiply a negative number. For example -6 and 6
-6 * 6
Multiply two negative numbers:
-5 * -7
If we multiply two negative numbers they turn positive.
Did you know the * symbol can also be used on other data types like strings and lists?
Multiplication
To divide two numbers we use the /. It’s also a binary operator, and we put a number then the / and then the other number. The number to the left is divided by the number to the right side of the symbol. For example let’s divide 60 by 12:
60 / 12
It’s giving us a double result. That’s necessary for representing the remainder of the division.
For example, 4 divided by 3
4 / 3
Integer division
At times we want the remainder of the division. This is called an integer division, meaning we get only a whole number back without any floating point. In this case we use the // operator.
Simply we put two forward slashes instead of one.
For example:
4 // 3
It’s giving us 1 instead of 1.333
Note: There is no rounding here. It will simply drop the numbers after the decimal point.
conclusion
In this post we saw how to use the classic arithmetic operators in Python. In particular, the Plus( + ) for addition, Minus (-) for subtraction, asterisk (*) for multiplication, forward slash (/) for division and double forward slashes (//) for integer division.
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Ellion
Professional IT consultant, writer, programmer enthusiast interested in all sorts of coding.
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