Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 76 · 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 − 308 =
2. 2.729 − 668 =
3. 3.503 − 198 =
4. 4.752 − 609 =
5. 5.637 − 337 =
6. 6.665 − 398 =
7. 7.867 − 198 =
8. 8.668 − 299 =
9. 9.831 − 598 =
10. 10.267 − 208 =
11. 11.876 − 698 =
12. 12.841 − 198 =
13. 13.395 − 247 =
14. 14.856 − 198 =
15. 15.874 − 199 =
16. 16.856 − 497 =
17. 17.866 − 499 =
18. 18.806 − 599 =
19. 19.638 − 427 =
20. 20.726 − 128 =
21. 21.971 − 797 =
22. 22.817 − 398 =
23. 23.965 − 698 =
24. 24.987 − 269 =
25. 25.414 − 399 =
26. 26.838 − 599 =
27. 27.468 − 299 =
28. 28.489 − 339 =
29. 29.911 − 799 =
30. 30.693 − 399 =
31. 31.459 − 399 =
32. 32.958 − 307 =
33. 33.983 − 797 =
34. 34.915 − 398 =
35. 35.613 − 237 =
36. 36.541 − 299 =
37. 37.485 − 198 =
38. 38.707 − 598 =
39. 39.714 − 699 =
40. 40.634 − 508 =

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