Young Einstein Mathematics Educational Software Contents

Activity Number 31

Heading : Subtraction To 20

Description : Subtracting numbers less than 20

Aim/Questions : Perform the subtraction.

Educational software theory used:

Subtraction To 20

When subtracting, you are calculating what will be left if you take away an amount. The final amount will be less than what you started with.

The  –  sign is used to represent the subtraction operation.

You can do subtraction by counting backwards from the starting number.

Eg

 17 - 5

If we had 17 to start with, lets count back 5 times.

16

15

14

13

12

The answer is 12.

If you get stuck, look at the picture and count the number of squares left highlighted.

Educational software Instruction :

1.  Subtract the number then type the difference into the ‘Answer Box’ provided.

2.  Press ‘Enter’ when you have finished.

Click on the ‘Wording’ check box if you want the sum written in a sentence.

Module 31. These Instructions from 'Young Einstein Mathematics educational software by Maths Practice are Copyright. Copyright Maths Practice P/L 2003 ©