Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 198 · 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. 1.359 − 199 =
2. 2.673 − 427 =
3. 3.670 − 497 =
4. 4.829 − 299 =
5. 5.875 − 697 =
6. 6.502 − 298 =
7. 7.402 − 338 =
8. 8.557 − 298 =
9. 9.981 − 299 =
10. 10.145 − 118 =
11. 11.590 − 399 =
12. 12.515 − 197 =
13. 13.650 − 577 =
14. 14.807 − 699 =
15. 15.624 − 399 =
16. 16.899 − 279 =
17. 17.987 − 597 =
18. 18.932 − 599 =
19. 19.818 − 699 =
20. 20.964 − 799 =
21. 21.667 − 399 =
22. 22.331 − 299 =
23. 23.488 − 399 =
24. 24.965 − 398 =
25. 25.547 − 399 =
26. 26.207 − 147 =
27. 27.633 − 587 =
28. 28.465 − 397 =
29. 29.676 − 297 =
30. 30.946 − 657 =
31. 31.531 − 199 =
32. 32.720 − 399 =
33. 33.963 − 299 =
34. 34.739 − 509 =
35. 35.534 − 198 =
36. 36.300 − 229 =
37. 37.765 − 287 =
38. 38.919 − 397 =
39. 39.843 − 428 =
40. 40.873 − 498 =

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