Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 334 · 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. 1.920 − 177 =
2. 2.980 − 497 =
3. 3.321 − 298 =
4. 4.775 − 259 =
5. 5.827 − 598 =
6. 6.398 − 318 =
7. 7.558 − 397 =
8. 8.660 − 448 =
9. 9.957 − 499 =
10. 10.917 − 797 =
11. 11.904 − 697 =
12. 12.241 − 188 =
13. 13.837 − 599 =
14. 14.395 − 297 =
15. 15.762 − 599 =
16. 16.939 − 578 =
17. 17.958 − 299 =
18. 18.966 − 297 =
19. 19.886 − 549 =
20. 20.664 − 458 =
21. 21.567 − 459 =
22. 22.497 − 379 =
23. 23.884 − 498 =
24. 24.857 − 199 =
25. 25.678 − 499 =
26. 26.596 − 498 =
27. 27.601 − 499 =
28. 28.386 − 199 =
29. 29.994 − 799 =
30. 30.596 − 358 =
31. 31.594 − 299 =
32. 32.951 − 599 =
33. 33.381 − 198 =
34. 34.641 − 469 =
35. 35.839 − 487 =
36. 36.316 − 199 =
37. 37.799 − 297 =
38. 38.921 − 198 =
39. 39.804 − 477 =
40. 40.739 − 277 =

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