Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 442 · 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. 1.993 − 399 =
2. 2.569 − 497 =
3. 3.811 − 367 =
4. 4.975 − 398 =
5. 5.752 − 398 =
6. 6.445 − 407 =
7. 7.936 − 599 =
8. 8.768 − 699 =
9. 9.213 − 198 =
10. 10.923 − 299 =
11. 11.808 − 639 =
12. 12.718 − 188 =
13. 13.388 − 259 =
14. 14.622 − 227 =
15. 15.719 − 317 =
16. 16.455 − 297 =
17. 17.498 − 319 =
18. 18.654 − 499 =
19. 19.769 − 187 =
20. 20.566 − 208 =
21. 21.506 − 249 =
22. 22.649 − 198 =
23. 23.653 − 518 =
24. 24.854 − 799 =
25. 25.399 − 199 =
26. 26.892 − 797 =
27. 27.332 − 299 =
28. 28.747 − 689 =
29. 29.835 − 668 =
30. 30.892 − 298 =
31. 31.488 − 399 =
32. 32.605 − 307 =
33. 33.941 − 319 =
34. 34.631 − 399 =
35. 35.726 − 299 =
36. 36.499 − 399 =
37. 37.842 − 187 =
38. 38.828 − 798 =
39. 39.708 − 668 =
40. 40.804 − 598 =

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