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Maths

Tuesday

 

WALT: use the inverse to find missing numbers in division sums.

 

Following on from yesterday, the inverse is the opposite which means the inverse of division is multiplication and the inverse of multiplication is division.  We can use the inverse to work our numbers missing from a calculation.

 

The information below is what is on yesterday's class page.

 

As we know, 6 x 3 = 18.  

From knowing this sum, we also know that:

3 x 6 = 18,

18 ÷ 3 = 6 and

18 ÷ 6 = 3

This uses the inverse to show different sums using the same numbers within a sum.

 

With division sums, it is a little more complicated than the multiplication ones we tried yesterday.  This is because it depends on where we find the question mark.  As a result, below you will find the 2 methods that can be used.

 

Method 1

 

For example, if we look at the following sum: ? ÷ 6 = 5,   we can use the inverse, being multiplication, to find the question mark.

 

For this to happen, you need to take the 2 numbers in the sum and multiply them together.  This means you need to multiply 5 x 6, which, as you know, equals 30.  We can check our sum by replacing the ? with the number 30 and seeing if the sum is correct.

 

METHOD 1 IS USED WHEN THE QUESTION MARK IS THE FIRST NUMBER!

 

Method 2

 

For example, if we look at the following sum: 18 ÷ ? = 9,   we actually still have to use division to find the question mark.

 

For this to happen, you need to take the 2 numbers in the sum and divide them.  This means you need to do 18 ÷ 9, which, as you know, equals 2.  We can check our sum by replacing the ? with the number 2 and seeing if the sum is correct.

 

METHOD 2 IS USED WHEN THE QUESTION MARK IS THE SECOND NUMBER!

 

it is important to remember that in division sums,

THE LARGEST NUMBER WILL ALWAYS BE THE FIRST NUMBER.

 

Today's task is to follow the link: https://www.ikidsmath.com/index.php/inverse-operation-division-number-0-to-10.  This shows 10 questions with missing numbers.  Please answer the questions but also write the multiplication or division sum that you have done to answer the question, depending on whether it is Method 1 or Method 2.  At the bottom of that page, there are other sets of questions that you can try, using harder times tables.  You can try these but don't worry if you cannot answer them, although you will be able to work out what sum you need to do.  Only try the questions that have division in their title.

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