Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 833 · 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. 1.598 − 567 =
2. 2.288 − 199 =
3. 3.908 − 198 =
4. 4.605 − 497 =
5. 5.990 − 578 =
6. 6.739 − 557 =
7. 7.772 − 428 =
8. 8.463 − 398 =
9. 9.950 − 399 =
10. 10.925 − 799 =
11. 11.341 − 297 =
12. 12.848 − 498 =
13. 13.684 − 598 =
14. 14.336 − 297 =
15. 15.811 − 547 =
16. 16.849 − 359 =
17. 17.831 − 599 =
18. 18.785 − 339 =
19. 19.558 − 199 =
20. 20.299 − 198 =
21. 21.964 − 498 =
22. 22.677 − 299 =
23. 23.980 − 797 =
24. 24.759 − 549 =
25. 25.705 − 397 =
26. 26.709 − 599 =
27. 27.737 − 628 =
28. 28.598 − 198 =
29. 29.381 − 278 =
30. 30.994 − 178 =
31. 31.648 − 197 =
32. 32.542 − 349 =
33. 33.942 − 597 =
34. 34.361 − 148 =
35. 35.598 − 197 =
36. 36.889 − 198 =
37. 37.817 − 299 =
38. 38.778 − 219 =
39. 39.628 − 398 =
40. 40.731 − 699 =

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