Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 339 · 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. 1.672 − 297 =
2. 2.886 − 328 =
3. 3.553 − 427 =
4. 4.753 − 698 =
5. 5.850 − 498 =
6. 6.915 − 318 =
7. 7.328 − 297 =
8. 8.759 − 597 =
9. 9.645 − 309 =
10. 10.881 − 698 =
11. 11.607 − 498 =
12. 12.496 − 308 =
13. 13.328 − 118 =
14. 14.522 − 447 =
15. 15.900 − 627 =
16. 16.951 − 589 =
17. 17.779 − 167 =
18. 18.911 − 249 =
19. 19.670 − 558 =
20. 20.386 − 297 =
21. 21.542 − 297 =
22. 22.277 − 118 =
23. 23.491 − 338 =
24. 24.541 − 149 =
25. 25.850 − 198 =
26. 26.846 − 497 =
27. 27.635 − 499 =
28. 28.142 − 117 =
29. 29.902 − 698 =
30. 30.557 − 448 =
31. 31.920 − 198 =
32. 32.572 − 497 =
33. 33.763 − 597 =
34. 34.750 − 497 =
35. 35.960 − 798 =
36. 36.707 − 197 =
37. 37.523 − 399 =
38. 38.744 − 407 =
39. 39.839 − 348 =
40. 40.749 − 139 =

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