Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 752 · 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. 1.392 − 179 =
2. 2.410 − 298 =
3. 3.808 − 597 =
4. 4.515 − 498 =
5. 5.771 − 179 =
6. 6.438 − 397 =
7. 7.555 − 389 =
8. 8.467 − 448 =
9. 9.848 − 798 =
10. 10.818 − 248 =
11. 11.688 − 409 =
12. 12.884 − 698 =
13. 13.437 − 349 =
14. 14.821 − 268 =
15. 15.881 − 698 =
16. 16.591 − 508 =
17. 17.915 − 497 =
18. 18.549 − 399 =
19. 19.879 − 619 =
20. 20.394 − 139 =
21. 21.745 − 199 =
22. 22.482 − 197 =
23. 23.922 − 799 =
24. 24.507 − 368 =
25. 25.747 − 527 =
26. 26.697 − 279 =
27. 27.436 − 398 =
28. 28.371 − 297 =
29. 29.786 − 198 =
30. 30.886 − 598 =
31. 31.530 − 298 =
32. 32.718 − 399 =
33. 33.921 − 799 =
34. 34.839 − 599 =
35. 35.361 − 199 =
36. 36.922 − 679 =
37. 37.333 − 198 =
38. 38.552 − 148 =
39. 39.707 − 468 =
40. 40.605 − 338 =

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