Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 629 · 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. 1.961 − 797 =
2. 2.868 − 699 =
3. 3.712 − 697 =
4. 4.758 − 468 =
5. 5.611 − 279 =
6. 6.777 − 507 =
7. 7.802 − 629 =
8. 8.642 − 178 =
9. 9.986 − 799 =
10. 10.962 − 129 =
11. 11.911 − 698 =
12. 12.416 − 198 =
13. 13.708 − 439 =
14. 14.545 − 509 =
15. 15.408 − 137 =
16. 16.942 − 679 =
17. 17.707 − 199 =
18. 18.991 − 158 =
19. 19.938 − 567 =
20. 20.295 − 127 =
21. 21.974 − 699 =
22. 22.752 − 597 =
23. 23.604 − 557 =
24. 24.796 − 597 =
25. 25.790 − 599 =
26. 26.993 − 799 =
27. 27.948 − 698 =
28. 28.963 − 799 =
29. 29.930 − 538 =
30. 30.958 − 667 =
31. 31.987 − 799 =
32. 32.976 − 699 =
33. 33.768 − 699 =
34. 34.947 − 798 =
35. 35.909 − 119 =
36. 36.672 − 597 =
37. 37.910 − 678 =
38. 38.748 − 638 =
39. 39.163 − 117 =
40. 40.539 − 477 =

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