Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 144 · 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. 1.823 − 469 =
2. 2.486 − 367 =
3. 3.904 − 297 =
4. 4.782 − 288 =
5. 5.471 − 197 =
6. 6.598 − 198 =
7. 7.519 − 197 =
8. 8.885 − 277 =
9. 9.531 − 309 =
10. 10.764 − 529 =
11. 11.890 − 189 =
12. 12.514 − 167 =
13. 13.480 − 299 =
14. 14.804 − 299 =
15. 15.935 − 798 =
16. 16.305 − 219 =
17. 17.892 − 307 =
18. 18.965 − 427 =
19. 19.958 − 698 =
20. 20.865 − 299 =
21. 21.336 − 237 =
22. 22.426 − 129 =
23. 23.592 − 199 =
24. 24.910 − 477 =
25. 25.425 − 197 =
26. 26.944 − 199 =
27. 27.944 − 679 =
28. 28.526 − 498 =
29. 29.631 − 549 =
30. 30.917 − 498 =
31. 31.534 − 348 =
32. 32.579 − 497 =
33. 33.919 − 699 =
34. 34.559 − 219 =
35. 35.578 − 197 =
36. 36.526 − 499 =
37. 37.640 − 399 =
38. 38.766 − 599 =
39. 39.546 − 249 =
40. 40.911 − 297 =

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