Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 956 · 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. 1.792 − 349 =
2. 2.288 − 199 =
3. 3.824 − 598 =
4. 4.646 − 549 =
5. 5.872 − 297 =
6. 6.922 − 799 =
7. 7.950 − 407 =
8. 8.800 − 699 =
9. 9.561 − 509 =
10. 10.682 − 208 =
11. 11.808 − 299 =
12. 12.730 − 507 =
13. 13.452 − 299 =
14. 14.860 − 119 =
15. 15.899 − 149 =
16. 16.693 − 398 =
17. 17.746 − 699 =
18. 18.810 − 597 =
19. 19.675 − 499 =
20. 20.752 − 679 =
21. 21.827 − 799 =
22. 22.293 − 199 =
23. 23.815 − 698 =
24. 24.642 − 259 =
25. 25.944 − 797 =
26. 26.895 − 498 =
27. 27.330 − 299 =
28. 28.371 − 199 =
29. 29.728 − 517 =
30. 30.647 − 399 =
31. 31.570 − 409 =
32. 32.699 − 169 =
33. 33.521 − 407 =
34. 34.684 − 569 =
35. 35.740 − 428 =
36. 36.634 − 599 =
37. 37.677 − 249 =
38. 38.922 − 299 =
39. 39.542 − 497 =
40. 40.818 − 247 =

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