Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 333 · 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. 1.864 − 427 =
2. 2.836 − 297 =
3. 3.861 − 699 =
4. 4.894 − 597 =
5. 5.414 − 197 =
6. 6.907 − 617 =
7. 7.685 − 399 =
8. 8.938 − 578 =
9. 9.815 − 798 =
10. 10.915 − 379 =
11. 11.826 − 498 =
12. 12.991 − 699 =
13. 13.827 − 499 =
14. 14.546 − 499 =
15. 15.621 − 547 =
16. 16.702 − 198 =
17. 17.754 − 497 =
18. 18.910 − 697 =
19. 19.463 − 199 =
20. 20.481 − 297 =
21. 21.502 − 357 =
22. 22.913 − 398 =
23. 23.748 − 399 =
24. 24.846 − 797 =
25. 25.682 − 597 =
26. 26.999 − 247 =
27. 27.468 − 197 =
28. 28.973 − 499 =
29. 29.876 − 298 =
30. 30.758 − 498 =
31. 31.566 − 547 =
32. 32.442 − 269 =
33. 33.910 − 429 =
34. 34.641 − 568 =
35. 35.570 − 397 =
36. 36.418 − 198 =
37. 37.869 − 797 =
38. 38.863 − 687 =
39. 39.809 − 399 =
40. 40.677 − 397 =

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