Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 421 · 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. 1.477 − 287 =
2. 2.711 − 297 =
3. 3.808 − 397 =
4. 4.877 − 498 =
5. 5.617 − 599 =
6. 6.996 − 697 =
7. 7.636 − 597 =
8. 8.391 − 269 =
9. 9.680 − 199 =
10. 10.951 − 179 =
11. 11.827 − 597 =
12. 12.764 − 659 =
13. 13.810 − 669 =
14. 14.966 − 798 =
15. 15.574 − 229 =
16. 16.784 − 699 =
17. 17.307 − 138 =
18. 18.346 − 328 =
19. 19.738 − 699 =
20. 20.384 − 218 =
21. 21.608 − 367 =
22. 22.548 − 199 =
23. 23.665 − 359 =
24. 24.794 − 137 =
25. 25.633 − 177 =
26. 26.992 − 298 =
27. 27.831 − 318 =
28. 28.896 − 798 =
29. 29.927 − 799 =
30. 30.462 − 398 =
31. 31.973 − 797 =
32. 32.484 − 298 =
33. 33.813 − 799 =
34. 34.885 − 398 =
35. 35.715 − 698 =
36. 36.827 − 297 =
37. 37.560 − 398 =
38. 38.984 − 549 =
39. 39.391 − 197 =
40. 40.915 − 298 =

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