Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 812 · 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. 1.861 − 798 =
2. 2.685 − 607 =
3. 3.405 − 228 =
4. 4.836 − 399 =
5. 5.807 − 399 =
6. 6.652 − 327 =
7. 7.951 − 797 =
8. 8.850 − 598 =
9. 9.313 − 229 =
10. 10.386 − 147 =
11. 11.777 − 199 =
12. 12.939 − 799 =
13. 13.642 − 368 =
14. 14.490 − 448 =
15. 15.555 − 479 =
16. 16.746 − 598 =
17. 17.561 − 498 =
18. 18.782 − 697 =
19. 19.789 − 338 =
20. 20.603 − 497 =
21. 21.885 − 198 =
22. 22.830 − 798 =
23. 23.674 − 499 =
24. 24.576 − 498 =
25. 25.638 − 497 =
26. 26.924 − 799 =
27. 27.727 − 577 =
28. 28.985 − 399 =
29. 29.440 − 328 =
30. 30.847 − 797 =
31. 31.467 − 309 =
32. 32.832 − 697 =
33. 33.623 − 197 =
34. 34.394 − 199 =
35. 35.322 − 199 =
36. 36.650 − 557 =
37. 37.891 − 799 =
38. 38.515 − 329 =
39. 39.853 − 797 =
40. 40.414 − 119 =

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