Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 647 · 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. 1.912 − 799 =
2. 2.797 − 599 =
3. 3.701 − 239 =
4. 4.696 − 399 =
5. 5.812 − 697 =
6. 6.932 − 799 =
7. 7.593 − 529 =
8. 8.697 − 497 =
9. 9.948 − 517 =
10. 10.853 − 699 =
11. 11.792 − 398 =
12. 12.700 − 497 =
13. 13.921 − 518 =
14. 14.999 − 277 =
15. 15.793 − 177 =
16. 16.954 − 799 =
17. 17.423 − 198 =
18. 18.770 − 298 =
19. 19.789 − 299 =
20. 20.741 − 697 =
21. 21.562 − 219 =
22. 22.926 − 447 =
23. 23.480 − 299 =
24. 24.299 − 158 =
25. 25.945 − 598 =
26. 26.680 − 598 =
27. 27.983 − 697 =
28. 28.731 − 517 =
29. 29.924 − 697 =
30. 30.881 − 689 =
31. 31.772 − 699 =
32. 32.522 − 339 =
33. 33.842 − 497 =
34. 34.609 − 507 =
35. 35.335 − 198 =
36. 36.826 − 259 =
37. 37.979 − 699 =
38. 38.561 − 479 =
39. 39.706 − 397 =
40. 40.478 − 388 =

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