# Python Key Skills - 2

## 1 Python Key Skills 2

### Learn It - for loops and while loops

• The purpose of loops is to repeat a set of commands or a block of code

#### for loops

• for loops are normally used to repeat a set of commands for a specific known number of times.
```for i in range(5):
print("Hello world!")
```
• the above code will print out "Hello world!" 5 times with i starting from 0, increasing each loop by 1, up to 4.
• the range is a Python built-in function that produce a series of numbers.

#### while loops

• while loops are normally used to repeat a set of commands until certain condition(s) are no longer true.
• Example while loop 1:
```i=0
while i < 5:
print("Hello world!")
i = i + 1
```
• Example while loop 2:
```hungry = True
while hungry:
print("I need eat more.")
answer = input("Are you still hungry?(Y/N)")
hungry = False
```
• The above loop will end if the user input "N", which changes the hungry variable to "False". This means, the condition is not true anymore.

### Learn It - check if a whole number is even or odd

• We know from maths that all even numbers can be divisible by 2. In other words, any even number, when divided by 2, the reminder should be 0 - no reminder.
• In Python, we have learned that the reminder operator is %. For example: 24%2 = 0; 25%2=1; 1%2=1 etc
• So if the reminder is 0 when divided by 2, then the number is even.
```myNum = int(input("Please give me a whole number: "))

if myNum % 2 == 0:
print("The number you game to me is an even number")
else:
print("The number you game to me is an odd number")
```