Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 848 · 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. 1.861 − 699 =
2. 2.551 − 528 =
3. 3.899 − 538 =
4. 4.780 − 497 =
5. 5.542 − 497 =
6. 6.798 − 147 =
7. 7.927 − 298 =
8. 8.916 − 609 =
9. 9.769 − 598 =
10. 10.844 − 658 =
11. 11.980 − 797 =
12. 12.621 − 499 =
13. 13.605 − 499 =
14. 14.811 − 699 =
15. 15.723 − 679 =
16. 16.429 − 199 =
17. 17.709 − 158 =
18. 18.975 − 598 =
19. 19.776 − 687 =
20. 20.796 − 517 =
21. 21.535 − 199 =
22. 22.817 − 598 =
23. 23.757 − 658 =
24. 24.801 − 458 =
25. 25.445 − 399 =
26. 26.734 − 497 =
27. 27.632 − 619 =
28. 28.751 − 579 =
29. 29.915 − 597 =
30. 30.428 − 199 =
31. 31.815 − 299 =
32. 32.814 − 499 =
33. 33.847 − 799 =
34. 34.759 − 399 =
35. 35.762 − 399 =
36. 36.566 − 277 =
37. 37.755 − 659 =
38. 38.987 − 797 =
39. 39.783 − 598 =
40. 40.312 − 198 =

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