Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 900 · 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. 1.741 − 558 =
2. 2.473 − 298 =
3. 3.485 − 399 =
4. 4.782 − 697 =
5. 5.259 − 218 =
6. 6.925 − 397 =
7. 7.879 − 597 =
8. 8.567 − 387 =
9. 9.388 − 297 =
10. 10.677 − 377 =
11. 11.626 − 489 =
12. 12.483 − 437 =
13. 13.441 − 318 =
14. 14.645 − 168 =
15. 15.969 − 399 =
16. 16.510 − 359 =
17. 17.863 − 798 =
18. 18.433 − 399 =
19. 19.333 − 199 =
20. 20.846 − 797 =
21. 21.800 − 599 =
22. 22.850 − 799 =
23. 23.951 − 238 =
24. 24.783 − 479 =
25. 25.430 − 399 =
26. 26.656 − 298 =
27. 27.821 − 259 =
28. 28.571 − 498 =
29. 29.310 − 189 =
30. 30.576 − 499 =
31. 31.614 − 297 =
32. 32.862 − 498 =
33. 33.665 − 609 =
34. 34.814 − 127 =
35. 35.690 − 609 =
36. 36.922 − 198 =
37. 37.749 − 368 =
38. 38.816 − 198 =
39. 39.982 − 199 =
40. 40.747 − 399 =

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