Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 989 · 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. 1.796 − 538 =
2. 2.978 − 699 =
3. 3.951 − 609 =
4. 4.588 − 118 =
5. 5.877 − 487 =
6. 6.743 − 477 =
7. 7.946 − 197 =
8. 8.970 − 689 =
9. 9.933 − 799 =
10. 10.723 − 697 =
11. 11.667 − 497 =
12. 12.554 − 328 =
13. 13.673 − 297 =
14. 14.901 − 137 =
15. 15.632 − 197 =
16. 16.731 − 199 =
17. 17.629 − 487 =
18. 18.727 − 299 =
19. 19.920 − 487 =
20. 20.637 − 197 =
21. 21.959 − 698 =
22. 22.923 − 248 =
23. 23.646 − 269 =
24. 24.992 − 697 =
25. 25.297 − 198 =
26. 26.777 − 319 =
27. 27.847 − 499 =
28. 28.841 − 798 =
29. 29.798 − 197 =
30. 30.601 − 499 =
31. 31.349 − 237 =
32. 32.547 − 199 =
33. 33.443 − 197 =
34. 34.733 − 667 =
35. 35.849 − 289 =
36. 36.710 − 498 =
37. 37.264 − 197 =
38. 38.857 − 497 =
39. 39.408 − 309 =
40. 40.654 − 298 =

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