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Python 4b - Mathematical Operators

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Modulo Division

The modulo operator - the percentage symbol % - will work out the remainder left over when one value is divided by another.

print(30 % 6)

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0

30 ÷ 6 = 5, which is a whole number, so there is no remainder and 0 is output.

print(30 % 7)

=

2

30 ÷ 7 = 4 remainder 2; so the remainder is output.

You can use modulo with variables too:

num1 = 33

num2 = 4

print("The remainder is" , num1 % num2)

The remainder is 1

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A common use of modulo is to check if a number is odd or even.

 

If a number has no remainder when divided by 2 then it is even.

=

num = int(input("Enter a number: "))

if num % 2 == 0:
 
print(num, "is even.")
else:
 
print(num , "is odd.")

Enter a number: 400

400 is even.

Enter a number: 191

191 is odd.

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Modulo Division Task 1 (Remainder)

Ask the user to input a whole number.

Use the modulo operator (%) to check if there is a remainder when the user's number is divided by 5Print the remainder.

Example solution:

Enter a number: 123
The remainder when divided by 5 is 3

Modulo Division Task 2 (Rollercoaster)

Use the odd/even program above to help solve this problem:

A rollercoaster only lets people on in groups of 4.

Ask the user to input a number for how many people are in their group.

 

Check if that number is directly divisible by 4 using modulo division (%). If it is then print “Perfect groups of four!” Else print “You will be split up”.

Example solutions:

Welcome to the Hyper Coaster!

How many in your group? 6
You will be split up!

Welcome to the Hyper Coaster!

How many in your group? 12
Perfect groups of four!

Integer Division

Integer division removes any decimal numbers when performing division, leaving just the integer (whole number).

In Python integer division is performed using //.

print(20 / 3)
print(20 // 3)

=

6.666666666666667
6

Integer Division Task 1 (Integer Division by 5)

Use an input line with int to ask the user to enter a number.

Use integer division (//) to divide the number by 5 without keeping any decimal values.

Challenge: Improve your solution by altering the print line to be more user friendly.

Example solutions:

Enter a number: 27
5

Enter a number: 27
5 goes into 27 5 times.

Integer Division Task 2 (Plane Rows)

A large plane has 6 seats in row.

Input the number of passengers on the plane and use integer division to work out how many full rows will be filled.

Example solution:

How many passengers are there in total? 174
There will be 29 full rows on the plane.

Exponent (Powers)

An exponent is the number of times a value is multiplied by itself, for example 2  = 2 x 2 x 2 = 8.

 

The symbol to represent an exponent in Python is **. For example: 4**2 represents 4   which is also 4 x 4.

3

2

print(4**4)

=

256

base = 5

exponent = 4

print(base**exponent)

625

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Exponent Task 1 (Square Number)

Use an input line with int to ask the user to enter a number.

Output the square of this number.

Example solution:

Enter a number: 12
12 squared is 144

Exponent Task 2 (Custom Exponent)

Use an input line with int to ask the user to enter a number, this will be the base.

 

Make another input line with int to ask for the exponent.

Use ** between the base and the exponent and print it.

Challenge: Make your solution better by including the base and exponent in the print line.

Example solutions:

Enter the base: 7
Enter the exponent: 3
343

Enter the base: 7
Enter the exponent: 3

7 to the power of 3 is 343

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