Page 306 - Artificial Intellegence_v2.0_Class_9
P. 306
Operator Precedence
An expression is made up of values, variables, operators and functions. For example,
x-5+6 is an expression
To evaluate an expression with multiple operators Python follows an order of precedence. This order can be
altered by writing an expression within parenthesis.
The order of precedence in the descending order is listed below:
Order of Precedence Operators
1 ()
2 **
3 */%//
4 +-
5 <= < > >=
6 == !=
7 = %= /= //= -= += *= **=
8 not, and, or
If an expression contains two or more operators with the same precedence, then order of evaluation is from left
to right except for exponential (**) which is always from right to left. For example,
• 10 – 2 + 3 – 3 will be evaluated from left to right as + and – has the same order of precedence. So, the answer
will be 10 – 2 will be 8 + 3 will be 11 – 3 will be 8.
• 2 ** 3 ** 2 will always be evaluated from right to left. It will be calculated as 2 ** (3 ** 2) and not as
(2 ** 3) ** 2. So, the answer will be 512.
Task
Solve the following expressions using the operator precedence:
• 10 + 20 / 5 – 3 * 2
• 5 * (10 + 5) + 10 – 5
Comments in Python
Comments are used to increase the readability of the code. We use them to give proper understanding of the
code in simple English statements. They are completely ignored by the Python interpreter. It is always a good
practice to add comments in your code so that if anybody in future wish to understand or modify your code,
then through comments it will be easy to interpret the instructions. There are two different ways of writing
comments in Python. Let us learn about them in detail.
Single Line Comment
Single line comment starts with hash symbol # followed by the text to be written as a comment that lasts till the
end of the line.
304 Touchpad Artificial Intelligence (Ver. 2.0)-IX

