Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 499 · 40 questions

How to do it in your head (Round up, add back): Round the number you take away up to the next ten or hundred: 297 → 300 (3 too many). Take away the round number. Add back the extra, because you took away too much.

1. 1.274 − 249 =
2. 2.675 − 298 =
3. 3.633 − 429 =
4. 4.339 − 297 =
5. 5.421 − 267 =
6. 6.821 − 798 =
7. 7.689 − 638 =
8. 8.277 − 179 =
9. 9.442 − 297 =
10. 10.710 − 137 =
11. 11.756 − 189 =
12. 12.679 − 567 =
13. 13.655 − 509 =
14. 14.693 − 199 =
15. 15.913 − 437 =
16. 16.759 − 307 =
17. 17.505 − 297 =
18. 18.403 − 337 =
19. 19.940 − 397 =
20. 20.849 − 619 =
21. 21.632 − 399 =
22. 22.835 − 498 =
23. 23.965 − 158 =
24. 24.859 − 599 =
25. 25.716 − 467 =
26. 26.824 − 349 =
27. 27.864 − 259 =
28. 28.896 − 697 =
29. 29.854 − 798 =
30. 30.439 − 188 =
31. 31.631 − 557 =
32. 32.978 − 489 =
33. 33.502 − 397 =
34. 34.882 − 609 =
35. 35.540 − 368 =
36. 36.857 − 797 =
37. 37.830 − 568 =
38. 38.922 − 517 =
39. 39.738 − 237 =
40. 40.969 − 239 =

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