Arithmetic and mathematics¶
Definition and syntax¶
The following symbols are used to do mathematics in Python. The symbols are known as operators because they perform operations on the numbers.
Symbol | Meaning | Example | Result |
---|---|---|---|
+ |
Addition | 5 + 5 |
10 |
- |
Subtraction | 10 - 3 |
7 |
* |
Multiplication | 20 * 3 |
60 |
/ |
Division | 5 / 2 |
2.5 |
// |
Integer division (divides and rounds down) | 15 % 6 |
2 |
% |
Modulus (gives the remainder after division) | 15 % 6 |
3 |
** |
Exponent / Power of | 5**2 |
25 |
Note
Notice in the examples how spaces can be used around mathematical operators to make code clearer.
Easy example¶
result = 15 + 5
No output is given from this code
Python does the calculation 15 + 5
and stores the result 20
in the variable result
.
Orders of precedence¶
Certain operations will be performed before others in Python. This is similar to how operations such as addition, multipication are carried out in mathematics. This is known as orders of precedence. You may know the term BIDMAS or BODMAS to remember the order.
The following table shows the orders of precedence. Operators at the top will be carried out before those underneath.
Operators | Description |
---|---|
( , ) |
Brackets / Parentheses |
** |
Exponentiation / Power |
* , / , % , // |
Multiplication, division, modulus, floor division |
+ , - |
Addition, subtraction |
< , <= , > , >= , != , == |
Comparison operators |
!= , == |
Equality operators |
not , and , or |
Boolean operators |
Examples¶
Example 3 - Brackets¶
answer = 15 * (3 - 1)
answer2 = 15 * 3 - 1
print(answer)
print(answer2)
30
44
Example 4 - Integer division¶
answer1 = 20 // 7
answer2 = 20 // 10
print(answer1)
print(answer2)
2
2
For answer1 = 20 % 7
, 7
goes into 20
twice. Therefore 2
is stored in answer1
then printed. This is integer division, so we do not store any fractions or decimal places.
For answer2 = 20 % 10
, 10
goes into 20
twice exactly. Therefore 2
is stored in answer2
then printed.
Example 5 - Modulus¶
answer1 = 20 % 7
answer2 = 20 % 10
print(answer1)
print(answer2)
6
0
For answer1 = 20 % 7
, 7
goes into 20
twice making 14
. The remainder from 20
is 6
which is stored in answer1
then printed.
For answer2 = 20 % 10
, 10
goes into 20
twice exactly. The remainder is therefore 0
which is stored in answer2
then printed.
Example 7 - Orders of precedence - without brackets¶
tempC = 37
tempF = tempC*9/5 + 32
print(tempF)
98.6
Example 8 - Orders of precedence - with and without brackets¶
answerA = 103 - 3 * 5 + 5
answerB = (103 - 3) * (5 + 5)
print(answerA)
print(answerB)
93
1000
Key points¶
Hint
The *
symbol is produced by pressing SHIFT-8
.