Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 129 · 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. 1.770 − 648 =
2. 2.509 − 397 =
3. 3.942 − 799 =
4. 4.767 − 178 =
5. 5.623 − 198 =
6. 6.994 − 599 =
7. 7.462 − 199 =
8. 8.635 − 218 =
9. 9.543 − 397 =
10. 10.457 − 267 =
11. 11.499 − 409 =
12. 12.456 − 299 =
13. 13.977 − 798 =
14. 14.639 − 297 =
15. 15.939 − 568 =
16. 16.368 − 158 =
17. 17.883 − 259 =
18. 18.411 − 129 =
19. 19.679 − 139 =
20. 20.533 − 298 =
21. 21.811 − 198 =
22. 22.525 − 398 =
23. 23.839 − 397 =
24. 24.608 − 547 =
25. 25.883 − 599 =
26. 26.664 − 398 =
27. 27.271 − 147 =
28. 28.846 − 588 =
29. 29.871 − 397 =
30. 30.816 − 497 =
31. 31.532 − 158 =
32. 32.400 − 199 =
33. 33.954 − 669 =
34. 34.704 − 598 =
35. 35.657 − 279 =
36. 36.328 − 298 =
37. 37.964 − 597 =
38. 38.691 − 199 =
39. 39.845 − 797 =
40. 40.627 − 297 =

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