Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 563 · 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. 1.565 − 459 =
2. 2.915 − 699 =
3. 3.822 − 198 =
4. 4.818 − 117 =
5. 5.823 − 799 =
6. 6.658 − 269 =
7. 7.893 − 557 =
8. 8.816 − 168 =
9. 9.634 − 398 =
10. 10.586 − 348 =
11. 11.727 − 698 =
12. 12.836 − 797 =
13. 13.693 − 498 =
14. 14.554 − 397 =
15. 15.956 − 578 =
16. 16.582 − 348 =
17. 17.753 − 637 =
18. 18.848 − 419 =
19. 19.786 − 647 =
20. 20.815 − 589 =
21. 21.542 − 487 =
22. 22.522 − 267 =
23. 23.251 − 157 =
24. 24.840 − 299 =
25. 25.692 − 669 =
26. 26.844 − 637 =
27. 27.779 − 197 =
28. 28.645 − 178 =
29. 29.785 − 497 =
30. 30.884 − 287 =
31. 31.981 − 597 =
32. 32.812 − 518 =
33. 33.866 − 507 =
34. 34.929 − 799 =
35. 35.736 − 539 =
36. 36.653 − 297 =
37. 37.543 − 199 =
38. 38.810 − 287 =
39. 39.764 − 199 =
40. 40.846 − 688 =

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