Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 718 · 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. 1.798 − 599 =
2. 2.773 − 597 =
3. 3.412 − 297 =
4. 4.518 − 459 =
5. 5.574 − 198 =
6. 6.688 − 187 =
7. 7.938 − 698 =
8. 8.950 − 799 =
9. 9.861 − 797 =
10. 10.483 − 457 =
11. 11.733 − 257 =
12. 12.656 − 399 =
13. 13.735 − 599 =
14. 14.876 − 197 =
15. 15.851 − 697 =
16. 16.961 − 207 =
17. 17.614 − 497 =
18. 18.913 − 198 =
19. 19.889 − 199 =
20. 20.587 − 497 =
21. 21.786 − 519 =
22. 22.867 − 447 =
23. 23.448 − 379 =
24. 24.789 − 598 =
25. 25.615 − 497 =
26. 26.397 − 298 =
27. 27.753 − 699 =
28. 28.437 − 218 =
29. 29.599 − 178 =
30. 30.767 − 688 =
31. 31.388 − 308 =
32. 32.939 − 647 =
33. 33.372 − 198 =
34. 34.586 − 497 =
35. 35.810 − 287 =
36. 36.639 − 599 =
37. 37.947 − 199 =
38. 38.970 − 548 =
39. 39.507 − 309 =
40. 40.542 − 189 =

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