Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 735 · 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. 1.846 − 429 =
2. 2.771 − 399 =
3. 3.735 − 539 =
4. 4.651 − 538 =
5. 5.871 − 797 =
6. 6.583 − 547 =
7. 7.751 − 697 =
8. 8.660 − 198 =
9. 9.795 − 609 =
10. 10.744 − 397 =
11. 11.364 − 119 =
12. 12.310 − 198 =
13. 13.818 − 697 =
14. 14.354 − 248 =
15. 15.919 − 279 =
16. 16.889 − 598 =
17. 17.907 − 507 =
18. 18.494 − 378 =
19. 19.525 − 199 =
20. 20.459 − 398 =
21. 21.974 − 618 =
22. 22.895 − 568 =
23. 23.919 − 799 =
24. 24.479 − 198 =
25. 25.660 − 598 =
26. 26.475 − 297 =
27. 27.939 − 568 =
28. 28.496 − 398 =
29. 29.715 − 299 =
30. 30.623 − 278 =
31. 31.916 − 598 =
32. 32.876 − 799 =
33. 33.536 − 498 =
34. 34.688 − 297 =
35. 35.339 − 308 =
36. 36.786 − 609 =
37. 37.920 − 637 =
38. 38.680 − 198 =
39. 39.506 − 298 =
40. 40.704 − 597 =

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