Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 568 · 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. 1.848 − 598 =
2. 2.322 − 117 =
3. 3.919 − 428 =
4. 4.638 − 599 =
5. 5.739 − 428 =
6. 6.668 − 397 =
7. 7.603 − 419 =
8. 8.604 − 298 =
9. 9.718 − 698 =
10. 10.372 − 297 =
11. 11.929 − 599 =
12. 12.896 − 298 =
13. 13.980 − 498 =
14. 14.887 − 797 =
15. 15.856 − 599 =
16. 16.923 − 798 =
17. 17.659 − 598 =
18. 18.699 − 619 =
19. 19.343 − 239 =
20. 20.648 − 617 =
21. 21.912 − 597 =
22. 22.230 − 198 =
23. 23.946 − 699 =
24. 24.681 − 439 =
25. 25.679 − 319 =
26. 26.847 − 428 =
27. 27.747 − 659 =
28. 28.648 − 549 =
29. 29.731 − 337 =
30. 30.950 − 529 =
31. 31.681 − 329 =
32. 32.608 − 129 =
33. 33.798 − 288 =
34. 34.753 − 699 =
35. 35.395 − 367 =
36. 36.948 − 799 =
37. 37.780 − 599 =
38. 38.574 − 207 =
39. 39.794 − 118 =
40. 40.305 − 197 =

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