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Multiplication Smorgasbord

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Multiplication Smorgasbord I am learning to solve multiplication problems using a variety of mental strategies. At a smorgasbord there are lots of different foods to ... – PowerPoint PPT presentation

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Title: Multiplication Smorgasbord


1
Multiplication Smorgasbord
I am learning to solve multiplication problems
using a variety of mental strategies.
At a smorgasbord there are lots of different
foods to choose from. You now know a lot of
different multiplication strategies. Now we are
going to try and choose the best strategy for
each question.
Work it out in your head
2
All the containers below hold 29 counters. How
many counters are there in total?
3 X 29 ?
There are a number of different ways we could
answer this problems.
Option 1
We could work out how many tens there are and how
many ones there are then add that amount together.
3 X 20 60
3 X 9 27
60 27 87
So 3 X 29 87
10
10
10
10
10
10
3
All the containers below hold 16 counters. How
many counters are there in total?
4 X 16 ?
Option 1
I dont know what 4 X 16 equals but I do know
that 4 X 8 32.
Since 8 is only half of 16 I must need to add
that same amount again.
4 X 16 (4 X 8 ) (4 X 8)
4 X 16 32 32
So 4 X 16 64
10
10
10
10
4
All the containers below hold 16 counters. How
many counters are there in total?
4 X 16 ?
Now lets try a different method.
Option 2
Im going to try doubling and halving.
This will mean there will be twice as many groups
(8) with half as many in each group (8)
4 X 16 ?
X2
2
8 X 8 64
So 4 X 16 64
10
10
10
10
5
Choose the best method for working out the
questions below and answer.
Click again when you have worked out all your
answers. A strategy for answering each of these
questions will be displayed. Please note that
this is only one possible solution. Your answer
however should be the same.
1) 4 X 25 ? 2) 3 X 27 ? 3) 6 X 39 ?
4) 7 X 22 ? 5) 4 X 24 ?
100, 2 X 50 100
81, 9 X 9 81
234, (6 X 40) (6 X 1 ) 234
154, (7 X 20) (7 X 2) 154
96, (4 X 12 48) double this amount.
Need some more practise? Try Pg34 35 of Teacher
Tools Multiplication and Division Book Numeracy
resources
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