Young Einstein Mathematics Educational Software Contents

Activity Number 49

Heading : Two Digit Subtraction - Pentagon

Description : Subtracting two 2 digit numbers

Aim/Questions : From the centre pentagon number subtract each layer to get the answers.

Educational software theory used:

Two Digit Subtraction - Pentagon

When subtracting larger numbers start with the ones units first.

When you have completed the ones units then move to the next column of tens units and subtract the tens units.

Eg

 6 2

-1 5

Firstly work on the ones units

 6 2

–1 5

     ?? I can’t do this.

Lets change 62 from 6 tens and 2 ones to 5 tens and 12 ones and try again.

 5 12

-1  5

    7

Now lets work on the tens units. But remember that you borrowed one lot of tens and you have only 5 left.

 5 12

-1  5

 4  7

Therefore

 62

–15

 47

Educational software Instruction :

1.  In the displayed pentagon, subtract each section from the centre placing your answer into each ‘Answer Box’ provided.

2.  Click ‘OK’ when you have finished.

It might be easier to have backwards entry enabled for this exercise.

Module 49. These Instructions from 'Young Einstein Mathematics educational software by Maths Practice are Copyright. Copyright Maths Practice P/L 2003 ©