Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 191 · 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. 1.906 − 609 =
2. 2.454 − 309 =
3. 3.972 − 197 =
4. 4.627 − 499 =
5. 5.804 − 697 =
6. 6.645 − 598 =
7. 7.556 − 249 =
8. 8.694 − 198 =
9. 9.696 − 668 =
10. 10.438 − 339 =
11. 11.861 − 298 =
12. 12.588 − 279 =
13. 13.899 − 358 =
14. 14.373 − 289 =
15. 15.858 − 648 =
16. 16.666 − 499 =
17. 17.773 − 297 =
18. 18.996 − 798 =
19. 19.963 − 637 =
20. 20.340 − 159 =
21. 21.726 − 689 =
22. 22.641 − 408 =
23. 23.658 − 609 =
24. 24.891 − 319 =
25. 25.985 − 799 =
26. 26.633 − 399 =
27. 27.812 − 698 =
28. 28.982 − 797 =
29. 29.999 − 669 =
30. 30.560 − 498 =
31. 31.640 − 499 =
32. 32.866 − 498 =
33. 33.291 − 207 =
34. 34.928 − 299 =
35. 35.886 − 697 =
36. 36.847 − 347 =
37. 37.769 − 499 =
38. 38.769 − 198 =
39. 39.584 − 397 =
40. 40.707 − 629 =

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