Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 881 · 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. 1.991 − 798 =
2. 2.489 − 398 =
3. 3.955 − 698 =
4. 4.905 − 797 =
5. 5.925 − 497 =
6. 6.824 − 557 =
7. 7.778 − 399 =
8. 8.812 − 797 =
9. 9.874 − 598 =
10. 10.849 − 699 =
11. 11.638 − 147 =
12. 12.647 − 198 =
13. 13.313 − 249 =
14. 14.482 − 297 =
15. 15.935 − 298 =
16. 16.932 − 797 =
17. 17.867 − 697 =
18. 18.268 − 189 =
19. 19.563 − 538 =
20. 20.401 − 298 =
21. 21.732 − 167 =
22. 22.980 − 537 =
23. 23.953 − 368 =
24. 24.539 − 399 =
25. 25.994 − 589 =
26. 26.775 − 578 =
27. 27.798 − 488 =
28. 28.283 − 238 =
29. 29.870 − 797 =
30. 30.677 − 488 =
31. 31.975 − 597 =
32. 32.654 − 319 =
33. 33.879 − 437 =
34. 34.891 − 217 =
35. 35.601 − 118 =
36. 36.783 − 699 =
37. 37.540 − 317 =
38. 38.937 − 599 =
39. 39.884 − 629 =
40. 40.832 − 799 =

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