Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 13 · 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. 1.505 − 388 =
2. 2.902 − 518 =
3. 3.871 − 398 =
4. 4.914 − 598 =
5. 5.686 − 467 =
6. 6.627 − 298 =
7. 7.558 − 199 =
8. 8.325 − 198 =
9. 9.571 − 499 =
10. 10.843 − 589 =
11. 11.950 − 797 =
12. 12.545 − 497 =
13. 13.931 − 698 =
14. 14.959 − 399 =
15. 15.822 − 699 =
16. 16.655 − 398 =
17. 17.891 − 688 =
18. 18.740 − 399 =
19. 19.919 − 399 =
20. 20.616 − 499 =
21. 21.844 − 597 =
22. 22.958 − 667 =
23. 23.871 − 699 =
24. 24.804 − 537 =
25. 25.642 − 259 =
26. 26.717 − 627 =
27. 27.933 − 488 =
28. 28.635 − 207 =
29. 29.966 − 339 =
30. 30.706 − 269 =
31. 31.416 − 147 =
32. 32.900 − 399 =
33. 33.548 − 418 =
34. 34.867 − 409 =
35. 35.618 − 299 =
36. 36.972 − 799 =
37. 37.469 − 298 =
38. 38.737 − 399 =
39. 39.840 − 799 =
40. 40.921 − 798 =

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