Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 747 · 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. 1.764 − 497 =
2. 2.541 − 198 =
3. 3.896 − 798 =
4. 4.877 − 797 =
5. 5.713 − 119 =
6. 6.933 − 797 =
7. 7.496 − 197 =
8. 8.941 − 547 =
9. 9.485 − 298 =
10. 10.601 − 497 =
11. 11.981 − 299 =
12. 12.917 − 299 =
13. 13.630 − 538 =
14. 14.851 − 517 =
15. 15.975 − 698 =
16. 16.692 − 569 =
17. 17.891 − 697 =
18. 18.482 − 247 =
19. 19.793 − 607 =
20. 20.764 − 698 =
21. 21.273 − 178 =
22. 22.212 − 159 =
23. 23.667 − 579 =
24. 24.480 − 328 =
25. 25.435 − 198 =
26. 26.706 − 587 =
27. 27.610 − 398 =
28. 28.561 − 298 =
29. 29.937 − 599 =
30. 30.979 − 597 =
31. 31.904 − 199 =
32. 32.923 − 598 =
33. 33.430 − 297 =
34. 34.751 − 297 =
35. 35.293 − 137 =
36. 36.577 − 399 =
37. 37.931 − 599 =
38. 38.740 − 628 =
39. 39.967 − 508 =
40. 40.972 − 799 =

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