Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 706 · 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. 1.769 − 699 =
2. 2.969 − 309 =
3. 3.475 − 459 =
4. 4.891 − 297 =
5. 5.672 − 598 =
6. 6.498 − 199 =
7. 7.909 − 649 =
8. 8.756 − 229 =
9. 9.991 − 599 =
10. 10.912 − 498 =
11. 11.650 − 199 =
12. 12.706 − 288 =
13. 13.938 − 799 =
14. 14.828 − 297 =
15. 15.361 − 309 =
16. 16.850 − 597 =
17. 17.574 − 498 =
18. 18.906 − 489 =
19. 19.724 − 579 =
20. 20.539 − 297 =
21. 21.592 − 297 =
22. 22.938 − 599 =
23. 23.817 − 197 =
24. 24.887 − 698 =
25. 25.607 − 397 =
26. 26.592 − 219 =
27. 27.879 − 599 =
28. 28.917 − 698 =
29. 29.736 − 598 =
30. 30.961 − 387 =
31. 31.860 − 589 =
32. 32.547 − 199 =
33. 33.741 − 368 =
34. 34.643 − 599 =
35. 35.809 − 119 =
36. 36.816 − 497 =
37. 37.913 − 639 =
38. 38.947 − 619 =
39. 39.894 − 248 =
40. 40.857 − 398 =

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