Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 739 · 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. 1.924 − 798 =
2. 2.788 − 299 =
3. 3.623 − 298 =
4. 4.997 − 457 =
5. 5.796 − 267 =
6. 6.791 − 598 =
7. 7.886 − 677 =
8. 8.349 − 297 =
9. 9.878 − 679 =
10. 10.826 − 797 =
11. 11.913 − 689 =
12. 12.847 − 797 =
13. 13.770 − 399 =
14. 14.970 − 497 =
15. 15.942 − 649 =
16. 16.789 − 598 =
17. 17.377 − 178 =
18. 18.693 − 399 =
19. 19.478 − 379 =
20. 20.551 − 228 =
21. 21.437 − 318 =
22. 22.522 − 497 =
23. 23.940 − 599 =
24. 24.560 − 399 =
25. 25.661 − 597 =
26. 26.919 − 479 =
27. 27.877 − 258 =
28. 28.835 − 799 =
29. 29.870 − 798 =
30. 30.641 − 387 =
31. 31.460 − 127 =
32. 32.408 − 328 =
33. 33.859 − 798 =
34. 34.971 − 538 =
35. 35.919 − 597 =
36. 36.957 − 699 =
37. 37.824 − 297 =
38. 38.881 − 638 =
39. 39.905 − 577 =
40. 40.745 − 158 =

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