Transcript A Little Bit Less

A Little Bit More/ A Little Bit Less
I am learning to solve multiplication problems by taking some off or
putting some on (compensation).
adding
subtracting
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.
6 x 5 = 30
We’re now going to use
6 X 5 = 30 to help us
answer 6 x 6 and 6 X 4.
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 5 = 30 Then add the amount counters we added. 6 X 1 = 6
30 + 6 = 36 so
6 X 6 = 36
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 5 = 30 Then take away the amount we crossed out 6 X 1 = 6
30 - 6 = 24 so
6 X 4 = 24
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
To solve 8 X 11 = ? we just add one more counter to each of the
8 groups.
8 x 10 = 80
Then add the amount counters we added.
8X1=8
80 + 8 = 88.
So 8 X 11 = 88
We can also use our knowledge of 8 X 10 = 80 to work out what
8X9=?
To solve 8 X 9 = ? we just remove one counter from each of the
8 groups.
8 x 10 = 80
Then subtract the amount of counters we
added.
8X1=8
80 - 8 = 72.
So 8 X 9 = 72
Now let’s try one together
7X6=?
Step 1: Imagine what this looks like. How many groups
there are and how many objects are in each group.
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
7X6=?
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.
You should be
imagining adding 1 to
each set.
Continued
7X6=?
Step 4: Put it all together.
7 X 5 = 35 and 7 X 1 = 7. How much do you have in total?
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)
48
2) 7 X 9 = ? (Hint: 7 X 10 = 70)
63
3) 8 X 4 = ? (Hint: 8 X 5 = 40)
32
4) 4 X 11 = ? (Hint: 4 X 10 = 40) 44
5) 6 X 9 = ? (Hint: 6 X 10 = 60)
54
Click again when you
have worked out all
your answers.
Now try these questions on your own.
1) 6 X 11 = ?
66
2) 8 X 9 = ?
72
3) 3 X 6 = ?
18
4) 7 X 6 = ?
42
5) 9 X 4 = ?
36
Click again when you
have worked out all
your answers.
Need some more practise? Try Pg23 & 24 of Teacher Tools Multiplication
and Division Book Numeracy resources