Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 381 · 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. 1.979 − 519 =
2. 2.429 − 288 =
3. 3.360 − 199 =
4. 4.446 − 298 =
5. 5.217 − 199 =
6. 6.794 − 398 =
7. 7.827 − 798 =
8. 8.375 − 299 =
9. 9.454 − 299 =
10. 10.963 − 297 =
11. 11.980 − 798 =
12. 12.539 − 289 =
13. 13.895 − 798 =
14. 14.968 − 267 =
15. 15.632 − 497 =
16. 16.900 − 699 =
17. 17.433 − 419 =
18. 18.412 − 299 =
19. 19.748 − 598 =
20. 20.820 − 698 =
21. 21.387 − 197 =
22. 22.725 − 397 =
23. 23.749 − 147 =
24. 24.783 − 498 =
25. 25.988 − 347 =
26. 26.960 − 597 =
27. 27.568 − 459 =
28. 28.959 − 597 =
29. 29.364 − 288 =
30. 30.733 − 599 =
31. 31.603 − 199 =
32. 32.868 − 497 =
33. 33.770 − 598 =
34. 34.414 − 297 =
35. 35.770 − 599 =
36. 36.798 − 199 =
37. 37.782 − 319 =
38. 38.400 − 378 =
39. 39.577 − 398 =
40. 40.559 − 497 =

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