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Lesson 3

Lesson 3 of 16

Operators

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Code Example

# Add (+)
print(5 + 2)
print(10 + 3)

# Subtract (-)
print(8 - 3)
print(10 - 4)

# Multiply (*)
print(4 * 2)
print(3 * 3)

# Divide (/)
print(8 / 2)
print(10 / 5)

Instructions

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The code editor is below.
The left side of the code editor is where you type your input code.
The right side of the code editor is where you see the output of your code.

Practice by typing the code example above, in the left side of the code editor below.
Then click the "Run Code" button, to run the code.
You will see the output of your code in the output section.

Python Code Editor

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Python can do math for us, like a calculator.
Operators are simply special symbols that can be used to do math.
The plus sign + means add.
The minus sign - means subtract.
The star * means multiply.
The slash / means divide.
We use print() to show the answer on the screen.
print(5 + 2) adds 5 and 2 and shows the answer.
print(8 - 3) takes 3 away from 8.
print(4 * 2) multiplies 4 and 2.
print(8 / 2) divides 8 by 2.
Each line does one math problem.
Python figures out the answer and prints it for us.

Code Example

print(10 % 3) 

print(8 % 4)

print(7 % 5)

Instructions

▲ ← Click the triangle to hide or reveal instructions.

The code editor is below.
The left side of the code editor is where you type your input code.
The right side of the code editor is where you see the output of your code.

Practice by typing the code example above, in the left side of the code editor below.
Then click the "Run Code" button, to run the code.
You will see the output of your code in the output section.

Python Code Editor

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Editor Input:

Editor Output:

Click "Run Code" to see the output here

The % symbol in Python is like a "leftovers" counter for math problems.
When you divide two numbers, the answer it gives you is the amount that is left over at the end.
For 10 % 3, Python sees that 3 fits into 10 three times, with 1 left over, so the answer is 1.
If a number fits perfectly with nothing left over, like 8 % 4, Python will give you a 0.
It is a super helpful tool when you want to check if a number is even or odd!

Code Example

number = 7
print(number % 2)
print(number % 2 == 0)
print(number % 2 == 1)  

number = 10
print(number % 2)
print(number % 2 == 0)
print(number % 2 == 1)

Instructions

▲ ← Click the triangle to hide or reveal instructions.

The code editor is below.
The left side of the code editor is where you type your input code.
The right side of the code editor is where you see the output of your code.

Practice by typing the code example above, in the left side of the code editor below.
Then click the "Run Code" button, to run the code.
You will see the output of your code in the output section.

Python Code Editor

Task Incomplete

Editor Input:

Editor Output:

Click "Run Code" to see the output here

You can use the % 2 trick to find out if a number is even or odd.
When you divide an even number by 2, there are 0 leftovers, so number % 2 will be 0.
When you divide an odd number by 2, there is always 1 leftover, so number % 2 will be 1.
We use == 0 to ask Python: "Is this number even?"
We use == 1 to ask Python: "Is this number odd?"
Python will answer your question with a simple True or False on the screen.

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Operators

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