Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 661 · 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. 1.704 − 297 =
2. 2.782 − 299 =
3. 3.405 − 157 =
4. 4.968 − 397 =
5. 5.956 − 597 =
6. 6.871 − 799 =
7. 7.341 − 298 =
8. 8.786 − 588 =
9. 9.396 − 339 =
10. 10.542 − 448 =
11. 11.616 − 398 =
12. 12.891 − 799 =
13. 13.439 − 407 =
14. 14.766 − 498 =
15. 15.827 − 498 =
16. 16.999 − 488 =
17. 17.464 − 298 =
18. 18.920 − 699 =
19. 19.831 − 498 =
20. 20.922 − 697 =
21. 21.399 − 297 =
22. 22.289 − 167 =
23. 23.619 − 237 =
24. 24.194 − 169 =
25. 25.888 − 398 =
26. 26.472 − 287 =
27. 27.915 − 699 =
28. 28.712 − 497 =
29. 29.718 − 428 =
30. 30.668 − 497 =
31. 31.899 − 307 =
32. 32.742 − 299 =
33. 33.679 − 317 =
34. 34.858 − 797 =
35. 35.320 − 149 =
36. 36.547 − 299 =
37. 37.837 − 499 =
38. 38.599 − 397 =
39. 39.567 − 409 =
40. 40.638 − 368 =

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