Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 606 · 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. 1.483 − 398 =
2. 2.646 − 207 =
3. 3.734 − 698 =
4. 4.997 − 199 =
5. 5.971 − 659 =
6. 6.686 − 119 =
7. 7.997 − 657 =
8. 8.962 − 597 =
9. 9.405 − 299 =
10. 10.338 − 289 =
11. 11.884 − 189 =
12. 12.989 − 379 =
13. 13.724 − 408 =
14. 14.617 − 278 =
15. 15.876 − 798 =
16. 16.644 − 499 =
17. 17.992 − 797 =
18. 18.773 − 409 =
19. 19.533 − 499 =
20. 20.919 − 577 =
21. 21.658 − 127 =
22. 22.879 − 467 =
23. 23.909 − 159 =
24. 24.654 − 299 =
25. 25.544 − 338 =
26. 26.635 − 599 =
27. 27.887 − 649 =
28. 28.637 − 597 =
29. 29.955 − 497 =
30. 30.644 − 357 =
31. 31.239 − 219 =
32. 32.828 − 299 =
33. 33.623 − 598 =
34. 34.647 − 397 =
35. 35.765 − 597 =
36. 36.853 − 597 =
37. 37.798 − 399 =
38. 38.994 − 449 =
39. 39.930 − 608 =
40. 40.817 − 799 =

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