Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 377 · 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. 1.933 − 798 =
2. 2.670 − 298 =
3. 3.428 − 209 =
4. 4.693 − 639 =
5. 5.831 − 799 =
6. 6.383 − 329 =
7. 7.936 − 797 =
8. 8.591 − 487 =
9. 9.951 − 387 =
10. 10.510 − 298 =
11. 11.511 − 349 =
12. 12.957 − 799 =
13. 13.765 − 319 =
14. 14.864 − 498 =
15. 15.728 − 537 =
16. 16.848 − 798 =
17. 17.436 − 397 =
18. 18.368 − 198 =
19. 19.672 − 598 =
20. 20.887 − 198 =
21. 21.850 − 799 =
22. 22.767 − 397 =
23. 23.428 − 198 =
24. 24.842 − 697 =
25. 25.572 − 288 =
26. 26.925 − 298 =
27. 27.665 − 617 =
28. 28.840 − 799 =
29. 29.246 − 198 =
30. 30.720 − 469 =
31. 31.587 − 499 =
32. 32.341 − 227 =
33. 33.950 − 798 =
34. 34.841 − 697 =
35. 35.665 − 299 =
36. 36.915 − 397 =
37. 37.727 − 698 =
38. 38.992 − 397 =
39. 39.994 − 468 =
40. 40.641 − 339 =

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