Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 971 · 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. 1.703 − 199 =
2. 2.421 − 168 =
3. 3.703 − 297 =
4. 4.905 − 599 =
5. 5.548 − 499 =
6. 6.764 − 398 =
7. 7.735 − 419 =
8. 8.724 − 669 =
9. 9.713 − 597 =
10. 10.987 − 309 =
11. 11.478 − 447 =
12. 12.794 − 699 =
13. 13.794 − 428 =
14. 14.940 − 157 =
15. 15.577 − 457 =
16. 16.770 − 497 =
17. 17.834 − 169 =
18. 18.764 − 499 =
19. 19.568 − 499 =
20. 20.938 − 797 =
21. 21.705 − 179 =
22. 22.492 − 399 =
23. 23.930 − 637 =
24. 24.737 − 398 =
25. 25.403 − 228 =
26. 26.666 − 499 =
27. 27.877 − 497 =
28. 28.970 − 338 =
29. 29.945 − 498 =
30. 30.568 − 399 =
31. 31.642 − 397 =
32. 32.753 − 599 =
33. 33.911 − 457 =
34. 34.998 − 698 =
35. 35.810 − 398 =
36. 36.727 − 599 =
37. 37.825 − 628 =
38. 38.934 − 398 =
39. 39.555 − 328 =
40. 40.826 − 699 =

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