Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 856 · 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. 1.440 − 298 =
2. 2.550 − 489 =
3. 3.366 − 298 =
4. 4.432 − 247 =
5. 5.552 − 399 =
6. 6.540 − 147 =
7. 7.999 − 699 =
8. 8.729 − 167 =
9. 9.883 − 598 =
10. 10.619 − 598 =
11. 11.702 − 399 =
12. 12.734 − 699 =
13. 13.759 − 599 =
14. 14.656 − 458 =
15. 15.846 − 698 =
16. 16.868 − 598 =
17. 17.916 − 597 =
18. 18.950 − 799 =
19. 19.620 − 199 =
20. 20.918 − 357 =
21. 21.957 − 499 =
22. 22.817 − 599 =
23. 23.669 − 199 =
24. 24.932 − 797 =
25. 25.841 − 298 =
26. 26.461 − 228 =
27. 27.510 − 327 =
28. 28.755 − 597 =
29. 29.899 − 479 =
30. 30.426 − 399 =
31. 31.446 − 339 =
32. 32.952 − 697 =
33. 33.282 − 219 =
34. 34.879 − 659 =
35. 35.459 − 359 =
36. 36.691 − 669 =
37. 37.713 − 169 =
38. 38.961 − 607 =
39. 39.746 − 198 =
40. 40.944 − 797 =

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