A Little Bit More/ A Little Bit Less

I am learning to solve multiplication problems by taking some off or putting some on (compensation).

subtractingadding

SAMPLE PROBLEM

To start with we’ll use our 5 times tables.

6 X 5 = 30. We know from earlier lessons that this means 6 groups of 5.

We’re now going to use 6 X 5 = 30 to help us answer 6 x 6 and 6 X 4.

6 x 5 = 30

SAMPLE PROBLEM

6 X 6 = ? We already have 6 X 5 = 30 to change it into 6 X 6 what do we have to do ?

Add one counter to each group, we now have 6 X 6

6 X 1 = 66 x 5 = 30

30 + 6 = 36 so

6 X 6 = 36

Then add the amount counters we added.

SAMPLE PROBLEM

We can also use 6 X 5 = 30 to help us work out the answer to 6 X 4= ? How many counters will we need to cross out from each group.

Crossing out one from each group leaves us with 6 X 4.

6 X 1 = 66 x 5 = 30

30 - 6 = 24 so

6 X 4 = 24

Then take away the amount we crossed out

We can also use our ten times tables to help us answer questions on our 9 times tables and 11 times tables.

Below are 8 groups of 10 counters or 8 x 10 = 80

80 + 8 = 88.So 8 X 11 = 88

To solve 8 X 11 = ? we just add one more counter to each of the 8 groups.

8 X 1 = 8

8 x 10 = 80

Then add the amount counters we added.

We can also use our knowledge of 8 X 10 = 80 to work out what

8 X 9 = ?

80 - 8 = 72.So 8 X 9 = 72

To solve 8 X 9 = ? we just remove one counter from each of the 8 groups.

8 X 1 = 8

8 x 10 = 80

Then subtract the amount of counters we added.

Now let’s try one togetherNow let’s try one together

Step 1: Imagine what this looks like. How many groups there are and how many objects are in each group.

7 X 6 = ?

Step 2: Think about what multiplication fact you know that might help you answer this question. Do this now.

You should be imagining 7 X 5 = 35

Continued

Step 3: Imagine how you could change 7 X 5 = 35 into

7 X 6 = ? How many do you need to add to each group? Imagine this now.

7 X 6 = ?

You should be imagining adding 1 to each set.

Continued

Step 4: Put it all together.

7 X 5 = 35 and 7 X 1 = 7. How much do you have in total?

7 X 6 = ?

35 + 7 = 42

So…

7 X 6 = 42

Now try these questions on your own. The question written in blue is a hint. This question should help you work out the answer

1) 8 X 6 = ? (Hint: 8 X 5 = 40)

2) 7 X 9 = ? (Hint: 7 X 10 = 70)

3) 8 X 4 = ? (Hint: 8 X 5 = 40)

4) 4 X 11 = ? (Hint: 4 X 10 = 40)

5) 6 X 9 = ? (Hint: 6 X 10 = 60)

Click again when you have worked out all your answers.

48

63

32

44

54

Now try these questions on your own.

1) 6 X 11 = ?

2) 8 X 9 = ?

3) 3 X 6 = ?

4) 7 X 6 = ?

5) 9 X 4 = ?

Click again when you have worked out all your answers.

66

72

18

42

36

Need some more practise? Try Pg23 & 24 of Teacher Tools Multiplication and Division Book Numeracy resources