Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 70 · 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. 1.732 − 297 =
2. 2.446 − 349 =
3. 3.700 − 429 =
4. 4.982 − 499 =
5. 5.785 − 398 =
6. 6.702 − 398 =
7. 7.860 − 799 =
8. 8.844 − 549 =
9. 9.983 − 597 =
10. 10.688 − 598 =
11. 11.390 − 299 =
12. 12.954 − 597 =
13. 13.685 − 397 =
14. 14.636 − 198 =
15. 15.632 − 289 =
16. 16.513 − 469 =
17. 17.915 − 688 =
18. 18.854 − 399 =
19. 19.959 − 198 =
20. 20.536 − 299 =
21. 21.512 − 499 =
22. 22.595 − 569 =
23. 23.859 − 799 =
24. 24.886 − 499 =
25. 25.540 − 468 =
26. 26.822 − 428 =
27. 27.729 − 587 =
28. 28.919 − 668 =
29. 29.879 − 358 =
30. 30.857 − 698 =
31. 31.686 − 599 =
32. 32.953 − 797 =
33. 33.975 − 797 =
34. 34.990 − 699 =
35. 35.968 − 799 =
36. 36.773 − 598 =
37. 37.707 − 197 =
38. 38.715 − 598 =
39. 39.921 − 638 =
40. 40.879 − 697 =

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