Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 273 · 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. 1.784 − 497 =
2. 2.718 − 377 =
3. 3.643 − 297 =
4. 4.933 − 798 =
5. 5.737 − 517 =
6. 6.723 − 617 =
7. 7.647 − 257 =
8. 8.899 − 379 =
9. 9.217 − 198 =
10. 10.382 − 297 =
11. 11.825 − 419 =
12. 12.894 − 468 =
13. 13.884 − 579 =
14. 14.939 − 498 =
15. 15.646 − 418 =
16. 16.848 − 698 =
17. 17.278 − 119 =
18. 18.716 − 697 =
19. 19.886 − 699 =
20. 20.581 − 267 =
21. 21.743 − 598 =
22. 22.475 − 267 =
23. 23.793 − 299 =
24. 24.522 − 198 =
25. 25.863 − 607 =
26. 26.853 − 487 =
27. 27.564 − 497 =
28. 28.724 − 699 =
29. 29.940 − 197 =
30. 30.947 − 598 =
31. 31.349 − 297 =
32. 32.930 − 278 =
33. 33.280 − 198 =
34. 34.631 − 539 =
35. 35.702 − 358 =
36. 36.965 − 397 =
37. 37.728 − 497 =
38. 38.990 − 398 =
39. 39.827 − 449 =
40. 40.574 − 498 =

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