Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 142 · 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. 1.717 − 699 =
2. 2.763 − 368 =
3. 3.807 − 119 =
4. 4.579 − 519 =
5. 5.666 − 599 =
6. 6.711 − 558 =
7. 7.603 − 519 =
8. 8.912 − 699 =
9. 9.637 − 548 =
10. 10.944 − 697 =
11. 11.696 − 167 =
12. 12.878 − 798 =
13. 13.902 − 698 =
14. 14.796 − 198 =
15. 15.517 − 199 =
16. 16.862 − 379 =
17. 17.710 − 269 =
18. 18.657 − 198 =
19. 19.685 − 597 =
20. 20.907 − 697 =
21. 21.597 − 297 =
22. 22.213 − 167 =
23. 23.829 − 259 =
24. 24.294 − 198 =
25. 25.458 − 297 =
26. 26.673 − 278 =
27. 27.583 − 498 =
28. 28.759 − 598 =
29. 29.522 − 499 =
30. 30.569 − 397 =
31. 31.733 − 628 =
32. 32.924 − 308 =
33. 33.830 − 589 =
34. 34.522 − 329 =
35. 35.676 − 338 =
36. 36.787 − 349 =
37. 37.809 − 599 =
38. 38.861 − 399 =
39. 39.871 − 277 =
40. 40.562 − 399 =

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