Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 657 · 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. 1.772 − 398 =
2. 2.770 − 298 =
3. 3.874 − 698 =
4. 4.844 − 798 =
5. 5.986 − 297 =
6. 6.323 − 308 =
7. 7.820 − 798 =
8. 8.993 − 297 =
9. 9.955 − 299 =
10. 10.892 − 479 =
11. 11.967 − 697 =
12. 12.606 − 368 =
13. 13.582 − 499 =
14. 14.955 − 697 =
15. 15.659 − 498 =
16. 16.886 − 298 =
17. 17.900 − 299 =
18. 18.973 − 399 =
19. 19.736 − 659 =
20. 20.929 − 287 =
21. 21.814 − 497 =
22. 22.905 − 599 =
23. 23.365 − 197 =
24. 24.906 − 798 =
25. 25.532 − 498 =
26. 26.840 − 117 =
27. 27.651 − 437 =
28. 28.515 − 499 =
29. 29.983 − 259 =
30. 30.975 − 548 =
31. 31.460 − 397 =
32. 32.898 − 398 =
33. 33.736 − 577 =
34. 34.954 − 568 =
35. 35.878 − 559 =
36. 36.815 − 659 =
37. 37.672 − 547 =
38. 38.739 − 399 =
39. 39.894 − 278 =
40. 40.635 − 497 =

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