Number
MULTIPLICATION BY 10, 100, 1000.
X 10
When multiplying whole numbers by 10 we write the number then add a
nought on the end.
e.g. (i)
2 x 10 = 20
 add a nought
Have a go at the exercise below.
A.
1)
3 x 10 =
2)
4 x 10 =
3)
6 x 10 =
4)
7 x 10 =
5)
9 x 10 =
Can you see the pattern?
e.g. (ii)
21 x 10
= 210
55 x 10
= 550
60 x 10
= 600
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Now have a go at these:
6)
32 x 10 =
7)
51 x 10 =
8)
19 x 10 =
9)
16 x 10 =
10)
81 x 10 =
11)
40 x 10 =
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Number
12)
30 x 10 =
13)
50 x 10 =
14)
122 x 10 =
15)
359 x 10 =
16)
428 x 10 =
17)
120 x 10 =
18)
210 x 10 =
19)
370 x 10 =
20) 560 x 10 =
21)
Toilet rolls cost 31 pence each. How much would it cost for a
pack of 10 rolls?
22) 10 friends go on holiday. The holiday costs them £220 each.
How much would that be altogether?
23) Sanjay collects 10 pence pieces in a jar. If he has collected
92, how much money does he have?
24) Kitchen tiles are 10cm wide, how long would a row of 25 tiles
be?
25) On average a match box holds 78 matches. How many would
there be in 10 boxes?
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X 100
B.
Work out the answers to the questions below
1)
2 x 100 =
2)
5 x 100 =
3)
6 x 100 =
4)
8 x 100 =
5)
7 x 100 =
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Number
Can you see the pattern?
When we x 100, we add 2 noughts to the end of the number.
e.g.
3 x 100 =
3 00
25 x 100 =
25 00
60 x 100 =
60 00
6)
9 x 100 =
7)
21 x 100 =
8)
35 x 100 =
9)
64 x 100 =
10)
29 x 100 =
11)
30 x 100 =
12)
40 x 100 =
13)
352 x 100 =
14)
621 x 100 =
15)
902 x 100 =
16)
100 people buy tickets costing £12 for a night out. How much
money is taken?
17)
6 friends go on a camping holiday. The holiday costs them
£100 each. How much money is this altogether?
18)
A train travels at an average of 100km per hour. How many
km will it go in 6 hours?
19)
In a survey of families, 100 parents said that they had 2
children each. How many children is this altogether?
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20) A supermarket buys tins of baked beans in batches of 100.
If they buy 19 batches, how many tins of baked beans is this?
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Number
x 1000
Can you guess how many noughts we add when we multiply a whole number by
1000?
C.
Have a go at these:
1)
2 x 1000 =
2)
3 x 1000 =
3)
8 x 1000 =
You add 3 noughts
e.g.
5 x 1000 =
5 000
21 x 1000 = 21 000
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Now have a go at these:
4)
9 x 1000 =
5)
24 x 1000 =
6)
36 x 1000 =
7)
29 x 1000 =
8)
84 x 1000 =
9)
20 x 1000 =
10)
60 x 1000 =
11)
324 x 1000 =
12)
215 x 1000 =
13)
601 x 1000 =
14)
439 x 1000 =
15)
10 x 1000 =
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Number
16)
A factory mkes 1000 cars in a week, if each car has 4 wheels,
how many wheels will they need?
17)
8 people win £1000 each in a competition. How much money is
this altogether?
18)
Kit Kats come in packs of 5 biscuits. A supermarket gets a
delivery of 1000 packs. How many biscuits is that
altogether?
19)
A concert is sold out. 1000 tickets have been sold at £8 each.
How much money has been taken altogether?
20) A box of pins holds 1000 pins. How many pins would there be
in 27 boxes?
Multiplication by 20, 30, 40 etc.
If we want to multiply by a number with a nought on the end, such as 20 or
30, we can use what we know about multiplying by 10 (i.e. adding a zero), then
just do a short multiplication.
If we want to multiply by 20.
We can x 2 then x by 10 by adding a nought
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so
1 x 20
2 x 20
12 x 20
is
is
is
1 x 2 = 2,
2 x 2 = 4,
12 x 2 = 24,
then add a nought
then add a nought
then add a nought
20
40
240
D.
Now have a go at the following exercise.
1)
4 x 20 =
2)
7 x 20 =
3)
13 x 20 =
4)
14 x 20 =
5)
24 x 20 =
6)
32 x 20 =
7)
13 x 30 =
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15 x 30 =
5
9)
39 x 30 =
Number
10)
44 x 30 =
11)
125 x 20 =
12)
64 x 50 =
13)
124 x 40 =
14)
201 x 60 =
15)
555 x 50 =
This method also works if we want to multiply by a number with 2 noughts on
the end, such as 200 or 300.
If we want to multiply by 400
we can x 4, then x 100 by adding 2 noughts
so
2 x 400
26 x 400
is
is
2 x 4 = 8,
26 x 4 = 104,
then x 100,
then x 100,
800
10400
E.
Now have a go at the exercise.
1)
8 x 200
2)
6 x 400
3)
2 x 700
4)
7 x 500
5)
9 x 300
6)
3 x 600
7)
12 x 200
8)
6 x 400
9)
7 x 500
10)
18 x 900
11)
27x 300
12)
40 x 700
13)
2 x 1600
14)
7 x 3500
15)
9 x 7800
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Check your answers, then discuss with your tutor what you need to
work on next.
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Number
Answers
Multiplication by 10, 100, 1000
A
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B
1)
30
2)
40
3)
60
4)
70
5)
90
6)
320
7)
510
8)
190
9)
160
10)
810
11)
400
12)
300
13)
500
14)
1220
15)
3590
16)
4280
17)
1200
18)
2100
19)
3700
20)
5600
21)
310p or £3.10
22)
£2200
23)
920p or £9.20
24)
250 cm
25)
780 matches
1)
200
2)
500
3)
600
4)
800
5)
700
6)
900
7)
2100
8)
3500
9)
6400
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Number
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C
10)
2900
11)
3000
12)
4000
13)
35200
14)
62100
15)
90200
16)
£1200
17)
£600
18)
600 km
19)
200 children
20)
1900 tins
1)
2000
2)
3000
3)
8000
4)
9000
5)
24000
6)
36000
7)
29000
8)
84000
9)
20000
10)
60000
11)
324000
12)
215000
13)
601000
14)
439000
15)
10000
16)
4000 wheels
17)
£8000
18)
5000 biscuits
19)
£8000
20)
27000 pins
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Number
D
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E
1)
80
2)
140
3)
260
4)
280
5)
480
6)
640
7)
390
8)
450
9)
1170
10)
1320
11)
2500
12)
3200
13)
4960
14)
12060
15)
27750
1)
1600
2)
2400
3)
1400
4)
3500
5)
2700
6)
1800
7)
2400
8)
2400
9)
3500
10)
16200
11)
8100
12)
28000
13)
3200
14)
24500
15)
70200
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