Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 825 · 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. 1.514 − 497 =
2. 2.885 − 698 =
3. 3.152 − 117 =
4. 4.278 − 258 =
5. 5.995 − 399 =
6. 6.847 − 697 =
7. 7.999 − 698 =
8. 8.735 − 699 =
9. 9.670 − 148 =
10. 10.630 − 599 =
11. 11.666 − 397 =
12. 12.959 − 398 =
13. 13.547 − 299 =
14. 14.759 − 499 =
15. 15.669 − 198 =
16. 16.821 − 798 =
17. 17.451 − 399 =
18. 18.428 − 399 =
19. 19.702 − 549 =
20. 20.879 − 508 =
21. 21.237 − 199 =
22. 22.990 − 697 =
23. 23.856 − 449 =
24. 24.537 − 309 =
25. 25.699 − 639 =
26. 26.567 − 459 =
27. 27.760 − 299 =
28. 28.977 − 369 =
29. 29.654 − 229 =
30. 30.585 − 499 =
31. 31.707 − 497 =
32. 32.911 − 518 =
33. 33.620 − 499 =
34. 34.975 − 628 =
35. 35.889 − 597 =
36. 36.947 − 667 =
37. 37.948 − 698 =
38. 38.839 − 467 =
39. 39.914 − 199 =
40. 40.954 − 548 =

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