Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 55 · 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. 1.833 − 298 =
2. 2.589 − 298 =
3. 3.574 − 499 =
4. 4.746 − 598 =
5. 5.714 − 299 =
6. 6.898 − 197 =
7. 7.790 − 399 =
8. 8.886 − 567 =
9. 9.778 − 599 =
10. 10.420 − 399 =
11. 11.902 − 647 =
12. 12.959 − 288 =
13. 13.977 − 339 =
14. 14.315 − 198 =
15. 15.497 − 438 =
16. 16.967 − 798 =
17. 17.620 − 559 =
18. 18.875 − 398 =
19. 19.902 − 697 =
20. 20.874 − 427 =
21. 21.307 − 197 =
22. 22.271 − 199 =
23. 23.236 − 199 =
24. 24.879 − 598 =
25. 25.886 − 417 =
26. 26.806 − 697 =
27. 27.857 − 799 =
28. 28.769 − 599 =
29. 29.999 − 497 =
30. 30.390 − 298 =
31. 31.766 − 117 =
32. 32.860 − 699 =
33. 33.680 − 599 =
34. 34.584 − 517 =
35. 35.697 − 297 =
36. 36.542 − 197 =
37. 37.627 − 397 =
38. 38.906 − 688 =
39. 39.594 − 418 =
40. 40.638 − 598 =

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