Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 41 · 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. 1.989 − 798 =
2. 2.620 − 148 =
3. 3.871 − 499 =
4. 4.998 − 678 =
5. 5.760 − 517 =
6. 6.642 − 199 =
7. 7.864 − 568 =
8. 8.928 − 409 =
9. 9.857 − 799 =
10. 10.756 − 379 =
11. 11.628 − 427 =
12. 12.435 − 358 =
13. 13.825 − 507 =
14. 14.555 − 299 =
15. 15.438 − 339 =
16. 16.859 − 799 =
17. 17.753 − 499 =
18. 18.723 − 677 =
19. 19.995 − 597 =
20. 20.400 − 198 =
21. 21.895 − 669 =
22. 22.318 − 197 =
23. 23.793 − 299 =
24. 24.964 − 669 =
25. 25.800 − 699 =
26. 26.922 − 229 =
27. 27.697 − 418 =
28. 28.752 − 599 =
29. 29.357 − 227 =
30. 30.246 − 199 =
31. 31.940 − 169 =
32. 32.723 − 558 =
33. 33.713 − 578 =
34. 34.918 − 399 =
35. 35.736 − 299 =
36. 36.834 − 398 =
37. 37.538 − 408 =
38. 38.913 − 599 =
39. 39.545 − 399 =
40. 40.889 − 199 =

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