Adding and Subtracting Strategies
Jumping past then back 
(1) 23 + □ = 71 23 + 50 = 73
73 – 2 = 71
and 50 - 2 = 48
so □ = 48 
(2) 12 + □ = 91 12 + 80 = 92
92 – 1 = 91
and 80 - 1 = 79
so □ = 79
Use the strategy of skipping on the number line to do these additions
Exercise 1
What to do:
• Do the problems in your head first.
• Check you are right by writing them down. Do them like the examples above, by marking an empty number line and jumping past using a tidy number then back.
(1) 23 + □ = 41 (2) 25 + □ = 61 (3) 25 + □ = 72
23 + 20 = 43 25 + 10 = 65 25 + 50 = 75
43 - 2 = 41 65 - 4 = 61 75 - 3 = 72
(4) 44 + □ = 82 (5) 46 + □ = 73 (6) 55 + □ = 81
44 + 40 = 84 46 + 30 = 46 55 + 30= 85
84 + 2 - 82 46 - 3 = 43 85 - 4 = 81
(7) 27 + □ = 64 (8) 36 + □ = 61 (9) 47 + □ = 71
27 + 30 = 67 36 + 30 = 66 47 + 30 = 77
67 - 3 = 64 66 - 3 = 63 77 - 6 = 71
(10) 17 + □ = 45 (11) 25 + □ = 81 (12) 29 + □ = 75
17 + 30 = 47 25 + 60 = 85 29 + 50 = 79
47 - 2 = 45 85 - 4 = 81 79 - 4 = 75
(13) 86 + □ = 172 (14) 125 + □ = 221 (15) 178 + □ = 265
86 + 90 = 176 125 + 100 = 225 178 + 100 = 278
176 - 4 = 172 225 - 4 = 221 278 - 13 = 265
(16) 58 + □ = 232 (17) 147 + □ = 471 (18) 324 + □ = 571
58 + 200 = 258 147 + 30 = 177 324 + 250 =574
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