Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 889 · 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. 1.574 − 498 =
2. 2.942 − 797 =
3. 3.977 − 148 =
4. 4.457 − 297 =
5. 5.586 − 408 =
6. 6.889 − 519 =
7. 7.479 − 137 =
8. 8.810 − 699 =
9. 9.902 − 698 =
10. 10.452 − 409 =
11. 11.872 − 598 =
12. 12.645 − 607 =
13. 13.730 − 647 =
14. 14.430 − 179 =
15. 15.502 − 398 =
16. 16.760 − 169 =
17. 17.645 − 499 =
18. 18.989 − 398 =
19. 19.850 − 799 =
20. 20.936 − 798 =
21. 21.386 − 297 =
22. 22.953 − 499 =
23. 23.937 − 499 =
24. 24.634 − 457 =
25. 25.357 − 198 =
26. 26.748 − 568 =
27. 27.941 − 118 =
28. 28.728 − 399 =
29. 29.814 − 697 =
30. 30.783 − 578 =
31. 31.771 − 409 =
32. 32.465 − 399 =
33. 33.603 − 328 =
34. 34.642 − 198 =
35. 35.468 − 449 =
36. 36.616 − 427 =
37. 37.722 − 397 =
38. 38.775 − 289 =
39. 39.560 − 497 =
40. 40.663 − 498 =

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