Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 721 · 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. 1.485 − 419 =
2. 2.550 − 529 =
3. 3.722 − 489 =
4. 4.918 − 298 =
5. 5.950 − 498 =
6. 6.302 − 227 =
7. 7.610 − 309 =
8. 8.477 − 199 =
9. 9.387 − 228 =
10. 10.883 − 368 =
11. 11.523 − 218 =
12. 12.801 − 257 =
13. 13.713 − 697 =
14. 14.339 − 197 =
15. 15.673 − 517 =
16. 16.290 − 197 =
17. 17.883 − 579 =
18. 18.364 − 189 =
19. 19.870 − 298 =
20. 20.632 − 499 =
21. 21.828 − 527 =
22. 22.902 − 299 =
23. 23.943 − 797 =
24. 24.963 − 268 =
25. 25.460 − 199 =
26. 26.994 − 298 =
27. 27.572 − 137 =
28. 28.385 − 198 =
29. 29.271 − 177 =
30. 30.770 − 257 =
31. 31.968 − 599 =
32. 32.823 − 357 =
33. 33.417 − 397 =
34. 34.489 − 318 =
35. 35.931 − 588 =
36. 36.935 − 598 =
37. 37.727 − 297 =
38. 38.994 − 507 =
39. 39.866 − 398 =
40. 40.720 − 459 =

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