Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 959 · 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. 1.904 − 797 =
2. 2.901 − 298 =
3. 3.838 − 798 =
4. 4.879 − 697 =
5. 5.827 − 299 =
6. 6.658 − 399 =
7. 7.513 − 178 =
8. 8.660 − 199 =
9. 9.935 − 157 =
10. 10.365 − 138 =
11. 11.801 − 698 =
12. 12.536 − 199 =
13. 13.823 − 298 =
14. 14.748 − 639 =
15. 15.710 − 649 =
16. 16.513 − 448 =
17. 17.556 − 299 =
18. 18.360 − 298 =
19. 19.795 − 597 =
20. 20.709 − 599 =
21. 21.971 − 397 =
22. 22.612 − 299 =
23. 23.846 − 197 =
24. 24.518 − 388 =
25. 25.284 − 137 =
26. 26.623 − 198 =
27. 27.753 − 157 =
28. 28.916 − 199 =
29. 29.728 − 609 =
30. 30.970 − 599 =
31. 31.748 − 698 =
32. 32.782 − 199 =
33. 33.581 − 497 =
34. 34.975 − 399 =
35. 35.460 − 298 =
36. 36.850 − 397 =
37. 37.994 − 697 =
38. 38.191 − 138 =
39. 39.773 − 418 =
40. 40.675 − 398 =

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