Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 49 · 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. 1.737 − 399 =
2. 2.875 − 699 =
3. 3.858 − 598 =
4. 4.520 − 499 =
5. 5.854 − 698 =
6. 6.702 − 198 =
7. 7.764 − 699 =
8. 8.908 − 199 =
9. 9.960 − 799 =
10. 10.565 − 497 =
11. 11.760 − 418 =
12. 12.730 − 398 =
13. 13.811 − 399 =
14. 14.774 − 698 =
15. 15.882 − 799 =
16. 16.476 − 198 =
17. 17.767 − 497 =
18. 18.954 − 689 =
19. 19.504 − 387 =
20. 20.453 − 297 =
21. 21.735 − 598 =
22. 22.721 − 308 =
23. 23.939 − 799 =
24. 24.795 − 397 =
25. 25.941 − 699 =
26. 26.460 − 199 =
27. 27.533 − 397 =
28. 28.756 − 217 =
29. 29.322 − 197 =
30. 30.741 − 697 =
31. 31.549 − 297 =
32. 32.883 − 557 =
33. 33.534 − 297 =
34. 34.381 − 297 =
35. 35.425 − 149 =
36. 36.836 − 197 =
37. 37.544 − 397 =
38. 38.607 − 569 =
39. 39.810 − 387 =
40. 40.640 − 347 =

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