Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 809 · 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. 1.405 − 299 =
2. 2.906 − 599 =
3. 3.838 − 299 =
4. 4.740 − 699 =
5. 5.711 − 298 =
6. 6.827 − 549 =
7. 7.531 − 498 =
8. 8.773 − 397 =
9. 9.451 − 298 =
10. 10.616 − 497 =
11. 11.569 − 497 =
12. 12.864 − 798 =
13. 13.413 − 299 =
14. 14.887 − 669 =
15. 15.482 − 298 =
16. 16.579 − 197 =
17. 17.919 − 298 =
18. 18.712 − 587 =
19. 19.776 − 667 =
20. 20.941 − 698 =
21. 21.263 − 237 =
22. 22.433 − 297 =
23. 23.963 − 547 =
24. 24.638 − 169 =
25. 25.845 − 699 =
26. 26.145 − 118 =
27. 27.731 − 698 =
28. 28.574 − 499 =
29. 29.893 − 699 =
30. 30.764 − 458 =
31. 31.547 − 497 =
32. 32.462 − 287 =
33. 33.971 − 279 =
34. 34.725 − 597 =
35. 35.669 − 589 =
36. 36.611 − 269 =
37. 37.286 − 199 =
38. 38.699 − 267 =
39. 39.750 − 397 =
40. 40.655 − 199 =

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