Year 2 Teaching Sequence Summer 5 - Add/subtract two-digit numbers by adding multiples of ten then adding the units using known addition facts (four days)
Prerequisites:
 Add/subtract multiples of ten to/from two-digit numbers (see oral and mental starter bank 5)
 Add/subtract 11, 12, 13, 21, 22, 23 by adding/subtracting 10/20 first (see spring teaching sequence 5)
 Use number facts to add single-digit numbers to two-digit numbers (e.g. 5 + 2 = 7, so 25 + 2 = 27, 5 – 2 = 3, so 35 - 2
= 33) (see oral and mental starter bank 5)
Overview of progression:
Children revise adding and subtracting 21, 22, and 23 to/from two-digit numbers using Jump (J10, adding/subtracting a two-digit number by counting on/back in tens first). They then use this strategy to add and subtract two-digit numbers on landmarked lines, then empty number lines. They are encouraged to add/subtract the units digit using knowledge of addition/subtraction facts and not counting in ones.
Note that the additions in this sequence are such that adding the units digit of the second number does not take the answer over the next multiple of ten, for example in 47 + 24, when working out 67 + 4 after adding 20, children cannot use a know addition fact with such ease, but probably need to bridge ten to add the four. The totals are also less than 100.
Note that it can be helpful to refer to steps of 10 as jumps, and steps of single-digit numbers as hops to reinforce the comparative size of each.
Note that some children will enjoy the freedom of drawing their own lines rather than having to locate numbers on landmarked lines.
Watch out for children whose counting on/back in tens or knowledge of addition and subtraction facts up to 10 are not secure enough to use this strategy. They will probably need more practice in adding and subtracting multiples of ten first.
© Original teaching sequence copyright Hamilton Trust, who give permission for it to be adapted as wished by individual users. Y2 Maths TS5 – Sum – 4 days

Objectives:
 Add/subtract two-digit numbers by adding/subtracting multiples of ten then one (e.g. add 45 and 23 by adding 20, then 3)
 Add a pair of two-digit numbers by putting the larger number first, e.g. 63 + 24
 Understand that addition can be done in any order, but not subtraction
Whole class
Write 53 + 21 on the board. Talk to your
partner about how we could work this out.
Take feedback and draw out using J10 to add on 20 then 2. Demonstrate how this can be shown on an ENL jotting, count on in tens from
53 to 73, label 73 and then add on 1:
+10 +10
+1
53 73 74
Write 45 + 22 on the board. Work with a partner to find the answer and draw a jotting on your whiteboard to show how you worked this out.
Repeat for 53 – 21 and 76 – 22, and then for
48 + 22, 39 + 22 and 61 – 22 where the addition/subtraction of two will take them to the next ten or over it.
Group activities
Group of 4-5 children
Write the following on f/c:
54 + = 74
67 + = 89
55 + = 78
44 + = 65
Write 20, 21, 22 and 23 on Post-its™.
These are the missing numbers. Which one goes in the first sentence? How
could we work it out? Take feedback which might include looking at the ones digits. Test out chn’s ideas drawing ENL to show the additions. Repeat with each sentence. Repeat with:
87 – = 67
95 – = 73
79 – = 58
65 – = 42
Easier: Show the addition and subtraction on a beaded line.
Harder:
Additions:
54 + = 74
67 + = 89
58 + = 81
49 + = 70
Paired/indiv practice
Ask chn to add and subtract 22 to and from the following numbers:
47, 65, 75, 34, 57, 67 and 77.
Chn record jottings on landmarked lines (see resources) or draw their own ENL.
Easier: Chn use beaded lines (see
resources).
Harder: Encourage chn to use
ENLs.
Resources
 Sheets of 0-
100 landmarked lines (see
resources)
 Sheets of 0-
100 beaded lines (see
resources)
 Post-its™
© Original teaching sequence copyright Hamilton Trust, who give permission for it to be adapted as wished by individual users. Y2 Maths TS5 – Sum – 4 days

What is 45 add 20? Do we need to count on in
ones? Ask a child to mark 45 on a landmarked line, and draw two jumps of ten, labelling them
+10, and labelling 65.
How do you think we could work out 45 add
24? Talk to your partner. Draw out that we can add 24 by adding on 20 as before, and then adding on 4. What number fact can we use to help? We know 5 add 4 is 9, so 65 add 4 is 69. So we still don’t need to count on in ones! We can use Jump 10 to add on any twodigit number.
Talk to your partner about how we might work
out 65 add 24. Take feedback. Draw this on the landmarked line, and then also as an empty number line (ENL) jotting:
+10 +10
+4
65 75 85 89
Say that chn may decide not to label 75, but just count on 20 in their heads, and label where they land afterwards, i.e. just label 85.
Repeat for 52 + 30, 52 + 33, 72 + 33 and 46 +
32, asking chn to help you to draw the jumps and hops on the landmarked line and to help you to sketch an ENL jotting.
Subtractions:
87 – = 67
95 – = 73
80 – = 59
63 – = 40
Group of 4-5 children
Write the following number sentences on the flipchart:
54 + = 76
54 + = 78
66 + = 89
66 + = 99
55 + = 87
55 + = 89
54 + = 79
54 + = 89
And write 22, 23, 24, 25, 32, 33, 34 and 35 on Post-its™. These are the missing numbers in these sentences.
Which one goes in the first sentence?
How could we work it out? Take feedback which might include looking at how many tens have been added, then ones. Use a landmarked line to test out chn’s ideas. Repeat with each sentence.
Easier: Show the addition on a beaded line.
Harder: Encourage chn to sketch an
ENL jotting to check.
Write the following additions on the board:
55 + 23, 55 + 33, 43 + 24, 43 +
34, 67 + 22, 67 + 32, 52 + 25, 52
+ 35, 52 + 45, 73 + 24.
Ask chn to work out these additions, recording jottings on landmarked lines (see resources).
Easier: Chn use beaded lines, and the jumps and hops are recorded on the first few examples (see
resources).
Harder: Encourage chn to use
ENLs.
 Large 0-100 landmarked line
(see resources)
 Large 0-100 beaded line
(see resources)
 Sheets of 0-
100 landmarked lines (see
resources)
 Post-its™
 Activity sheet of 0-100 beaded lines
(see resources)
Go Maths Activity pages 49 and 50
© Original teaching sequence copyright Hamilton Trust, who give permission for it to be adapted as wished by individual users. Y2 Maths TS5 – Sum – 4 days

What is 65 take away 20? Do we need to count
back in ones? Ask a child to mark 65 on a landmarked line, and draw two jumps of ten, labelling them -10, and labelling 45.
How do you think we could work out 65 take
away 24? Talk to your partner. Draw out that we can subtract 24 by taking away 20 as before, and then taking away 4. What number fact can we use to help? We know 5 take away
4 is one, so 45 take away 4 is 41. So we still don’t need to count back in ones! We can use
Jump 10 to subtract any two-digit number.
Talk to your partner about how we might work
out 85 take away 24. Take feedback. Draw this on the landmarked line, and then also as an ENL jotting:
-4
-10 -10
61 65 75 85
Say that chn may not label 75, but just count on ten in their heads, and label where they land afterwards, i.e. just label 65.
Repeat for 85 - 30, 85 - 33, 77 - 33 and 96 -
32, asking chn to help you to draw the jumps and hops on the landmarked line and to help you to sketch an ENL jotting.
Write 21 + 67 on the board. Talk to your
partner about how you might work this out.
Take feedback. Discuss how 67 is quite a lot to add on, but that you could start with 67 and add 21 on instead. Show both on the landmarked line to show that the answer to
Group of 4-5 children
Write the following number sentences on the flipchart:
95 - = 73
95 - = 63
87 - = 64
87 - = 62
68 - = 44
68 - = 34
76 - = 43
76 - = 41
And write 22, 23, 24, 25, 32, 33, 34 and 35 on Post-its™. These are the missing numbers in these sentences.
Which one goes in the first sentence?
How could we work it out? Take feedback which might include looking at how many tens have been subtracted, then ones. Use a landmarked line to test out chn’s ideas. Repeat with each sentence.
Easier: Show the subtraction on a beaded line.
Harder: Encourage chn to sketch an
ENL jotting to check.
Group of 4-5 children
Show 63p made using coins. You buy a drink for 63p pence. You also buy an
apple for 23p. Move two 10p coins next to the 63p saying seventy-three, eighty-three, and the three pence,
Write the following subtractions on the board:
78 - 23, 78 - 33, 67 - 24, 67 - 34,
56 - 22, 56 - 32, 98 - 25, 98 - 35,
95 - 42, 79 - 24.
Ask chn to work out these subtractions, recording jottings on landmarked lines (see
resources).
Easier: Chn use beaded lines, and the jumps and hops are recorded on the first few examples (see
resources).
Harder: Encourage chn to use
ENLs.
Chn practise adding and subtracting two-digit numbers using J10.
Write the following on the board, and ask them to choose landmarked or ENL jottings to
 Large 0-100 landmarked line
(see resources)
 Large 0-100 beaded line
(see resources)
 Sheets of 0-
100 landmarked lines (see
resources)
 Post-its™
 Activity sheet of 0-100 beaded lines
(see resources)
 Large 0-100 landmarked line
(see resources)
 Real coins less than £1
 0-£1 penny line
© Original teaching sequence copyright Hamilton Trust, who give permission for it to be adapted as wished by individual users. Y2 Maths TS5 – Sum – 4 days

both is the same, (drawing jumps and the hop above the line for one way, and jumps and hop below the line). Which way was easier?
Addition works either way, so we can choose
which way is easier. Write the following additions on the board: 23 + 56, 62 + 35, 45 +
31, 34 + 52.
Ask chn to discuss in pairs which number they would put first and to write this on their whiteboards. Take feedback.
Addition works either way around. Do you
think subtraction does? Write 67 – 21 and 21 –
67 on the board. Do you think the answer to
these will be the same? Talk to your partner.
Take feedback, and show 67 – 21 on the landmarked line, and then try to subtract 67 from 21. We run out of number line! So the
answer isn’t the same. saying 86p. Ask chn to look at the coins to check the total. Record the steps on a 0-£1 penny line (see resources).
Repeat with similar additions.
This time you have 85p. Make 85p using
50p, three 10ps and a 5p coin. You buy a banana for 33p. Move away three 10p coins as you count back in tens. Now we have to take away three. What can we
do? What is 5 take away three? Remove the 5p coins, and replace with a 2p coin.
Repeat with similar subtractions.
Easier: Make the amounts only using 10p and 1p coins. solve them:
22 + 85, 54 + 25, 32 + 64, 46 +
34, 35 + 42, 96 – 25, 75 – 34, 87 –
24, 98 – 35, 95 – 42.
Easier: Choose beaded or landmarked lines.
Harder: Chn add and subtract some numbers which require them to cross a multiple of ten when adding/subtracting the ones part of the number, e.g. 47 + 25 and
72 – 24 (see Activity sheet in
resources).
(see resources)
 Sheets of 0-
100 landmarked lines (see
resources)
 Sheets of 0-
100 beaded lines (see
resources)
 Activity sheet
(see resources)
Go Maths PCMs
73 and 74 and
Activity book page
57
© Original teaching sequence copyright Hamilton Trust, who give permission for it to be adapted as wished by individual users. Y2 Maths TS5 – Sum – 4 days