Adding Up

Category 1 Adding Up strategy : The whole number is a multiple of ten or one hundred. The subtrahend is close to a multiple of ten or a landmark number.

20 – 15 20 – 14 20 – 9 20 – 8

30 – 24 30 – 19 30 – 15 30 – 12

40 – 34 40 – 29 40 – 24 40 – 19

50 – 44 50 – 39 50 – 29 50 – 24

60 – 54 60 – 49 60 – 39 60 – 29

70 – 59 70 – 49 70 – 39 70 – 34

80 – 69 80 – 59 80 – 49 80 – 39

90 – 79 90 – 74 90 – 49 90 – 44

100 – 89 100 – 74 100 – 49 100 – 44

Category 2 Adding Up strategy : The whole number is a multiple of ten or one hundred. The subtrahend is close to a multiple of ten or a landmark number.

100 – 89 100 – 69 100 – 49 100 – 37

150 – 124 150 – 149 150 – 99

250 – 224 250 – 219 200 – 199 200 – 149

300 – 269 300 – 249 300 – 99 300 – 149

400 – 349 400 – 299 400 – 274 200 – 199

500 – 449 500 – 419 500 – 299 500 – 249

750 – 709 750 – 599 750 – 449 750 – 324

1000 – 899 1000 – 749 1000 – 624 1000 – 499

Category 3 Adding Up strategy : The whole number is NO longer an exact multiple of ten or one hundred. The subtrahend is farther distance from the whole.

50 – 29 50 – 48 50 – 37

80 – 59 84 – 59 81 – 48 81 – 36

70 – 49 73 – 49 76 – 67 76 – 39

100 – 75 120 – 75 125 – 75 125– 83

100 – 80 140 – 80 146 – 80 146– 89

200 – 149 250 – 149 223 – 186 245– 198

300 – 174 315 – 174 335 – 219 335– 287

400 – 329 420 – 329 423 – 318 444 – 298

500 – 249 525 – 249 1000 – 499 1000 – 671