Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 308 · 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. 1.452 − 389 =
2. 2.865 − 668 =
3. 3.697 − 377 =
4. 4.889 − 799 =
5. 5.976 − 798 =
6. 6.739 − 699 =
7. 7.675 − 598 =
8. 8.793 − 529 =
9. 9.816 − 339 =
10. 10.823 − 597 =
11. 11.564 − 428 =
12. 12.991 − 798 =
13. 13.998 − 148 =
14. 14.967 − 799 =
15. 15.438 − 397 =
16. 16.443 − 397 =
17. 17.604 − 497 =
18. 18.700 − 599 =
19. 19.876 − 697 =
20. 20.793 − 599 =
21. 21.530 − 419 =
22. 22.722 − 699 =
23. 23.826 − 667 =
24. 24.587 − 397 =
25. 25.364 − 338 =
26. 26.828 − 797 =
27. 27.250 − 188 =
28. 28.788 − 497 =
29. 29.936 − 438 =
30. 30.962 − 399 =
31. 31.715 − 257 =
32. 32.511 − 397 =
33. 33.810 − 587 =
34. 34.748 − 667 =
35. 35.965 − 699 =
36. 36.942 − 199 =
37. 37.824 − 697 =
38. 38.893 − 797 =
39. 39.991 − 299 =
40. 40.555 − 398 =

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