Addition and Subtraction

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(No Transcript)
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Lets get started Its Mental Maths Time!
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Addition
How many altogether?
and
more
total
add
increase
sum
plus
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Partitioning
35 28 35 30 5 28 20 8 30 20 50 58
13 50 13 63
This method can also be used for HTU
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Using a Number Line to Add Two Digit Numbers

• Start by adding the tens number, then adding
  the units number. This is first introduced on
  number line with all the numbers shown. If you
  do not have one of these at home use a ruler.
  Once a child is confident with the method, there
  is no need to write out all the numbers on the
  line.

10
2
22 12 34
22 32
34
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Column Addition with Carrying from Units to Tens
It is important that numbers are lined up in
columns carefully. We always work from right to
left. Any carrying is placed below the bottom
line.

• 2 3 4
• 3 5 7
• 1

5
1
9
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Column Addition with 3 Digit Numbers, Carrying
from all Columns

• 8 3 4
• 4 6 7
• 1

1
1 3
0
1
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Column Addition with Numbers with One Decimal
Place

• 8 3 4
• 4 6 7

It is important to line up the decimal point in
each number when setting out the sums. Remember
to place a decimal point in the answer.
1
0
1 3
1
1
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Subtraction
decrease
subtract
Difference
less
fewer
minus
take away
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Using a Number Line to Subtract 2 Digit Numbers

• Start by subtracting the tens number, then
  subtract the units number. This is first
  introduced on a number line with all the numbers
  shown. If you do not have one of these at home
  use a ruler. Once a child is confident with the
  method, there is no need to write out all the
  numbers on the line.

- 10
-2
34-12 22
22 24
34
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Column Subtraction with Exchange from Tens to
Units Column
7

• 5 8 4
• - 3 5 7

1
2 2 7
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Column Subtraction with Exchange from all Columns
7
4
1

• 5 8 4
• - 3 9 7

1
1
8 7
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Column Subtraction with Decimal Numbers with One
Decimal Place and Exchange from all Columns
7
4
1

• 5 8 4
• - 3 9 7

1
It is important to line up the decimal points
when setting up calculations with decimal numbers
7
8
1
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Multiplication
How many lots of?
product
times
multiplied by
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Using the Grid Method to Multiply by a Single
Digit

• First draw out a grid. It is only really
  necessary to draw out the red lines below. The
  grid can be used for numbers with any amount of
  digits

20
3
x
e.g. 23x7


7
140
21
161
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Using the Grid Method to Multiply by Two Digits

• First draw out a grid. It is only really
  necessary to draw out the red lines below. The
  grid can be used for numbers with any amount of
  digits

20
3
x
e.g. 23x37


690
600
90
30



7
140
21
161
Your child may wish to use this standard way to
multiply numbers with more than one digit once
they understand how numbers are partitioned. Of
course, they may prefer to continue using this
grid method instead.
851
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Using Column Multiplication

3 4 6 X 5
Once confident and with an understanding of how
numbers are partitioned when multiplying, your
child will be encouraged to use this standard way
to multiply single digit numbers
0
3
1 7
3
2
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Using Column Multiplication when Multiplying by a
Two Digit Number

Your child may wish to use this standard way to
multiply numbers with more than one digit once
they understand how numbers are partitioned.
However, they may prefer to continue using this
grid method instead.
3 4 6 X 2 5
0
3
1 7

3
2
0
2
9
6
1
8
0
5
6
1
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Using Column Multiplication with Decimal numbers

3 4 6 X 5

0
3
1 7

3
2
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Division
How many groups are in..?
shared by
quotient
into
divided by
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Sharing a Number
8 divided by 4 2
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Chunking
72 divided by 3
72
0
3
3
3
3
10x3
10x3
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Using Arrays

• An array is an arrangement of a number or
  counters represented as a rectangle. The number
  of rows and columns show the numbers it can be
  divided by. For example, lets consider the
  number 12. It can be visually represented in an
  array like this

So, 12 2 6
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Interpreting Arrays
By showing division in this way and by ringing
columns rather than rows, it is very clear to see
that 12 6 2 By ringing columns instead of
rows the introduction to thinking of division as
grouping can be made
12 divided by 2 6
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Locating Division Facts from a Multiplication
Square
x 1 2 3 4 5 6 7 8 9 10 11 12
1 1 2 3 4 5 6 7 8 9 10 11 12
2 2 4 6 8 10 12 14 16 18 20 22 24
3 3 6 9 12 15 18 21 24 27 30 33 36
4 4 8 12 16 20 24 28 32 36 40 44 48
5 5 10 15 20 25 30 35 40 45 50 55 60
6 6 12 18 24 30 36 42 48 54 60 66 72
7 7 14 21 28 35 42 49 56 63 70 77 84
8 8 16 24 32 40 48 56 64 72 80 88 96
9 9 18 27 36 45 54 63 72 81 90 99 108
10 10 20 30 40 50 60 70 80 90 100 110 120
11 11 22 33 44 55 66 77 88 99 110 121 132
12 12 24 36 48 60 72 84 96 108 120 132 144

• To find the answer to 42 7
• Look across the top for the 7 column
• Go down the x7 column until you find 42
• Read across to see how many groups of 7 made 42

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Standard Division (no remainders)
2
3
2
4
We always work from left to right
2
4 6 4 8
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Standard Division (with a remainder in the
answer)
r 1
2
3
2
4
2
4 6 4 9
Place the remainder after the letter r at the
end of the answer