Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 976 · 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. 1.933 − 799 =
2. 2.594 − 397 =
3. 3.689 − 498 =
4. 4.705 − 598 =
5. 5.935 − 319 =
6. 6.919 − 148 =
7. 7.685 − 297 =
8. 8.492 − 299 =
9. 9.565 − 439 =
10. 10.387 − 297 =
11. 11.793 − 299 =
12. 12.837 − 498 =
13. 13.943 − 158 =
14. 14.979 − 797 =
15. 15.815 − 247 =
16. 16.684 − 599 =
17. 17.540 − 399 =
18. 18.711 − 498 =
19. 19.766 − 299 =
20. 20.693 − 198 =
21. 21.642 − 297 =
22. 22.997 − 349 =
23. 23.590 − 499 =
24. 24.939 − 699 =
25. 25.690 − 488 =
26. 26.746 − 398 =
27. 27.644 − 219 =
28. 28.770 − 199 =
29. 29.860 − 799 =
30. 30.568 − 499 =
31. 31.719 − 199 =
32. 32.891 − 598 =
33. 33.880 − 598 =
34. 34.643 − 569 =
35. 35.351 − 158 =
36. 36.598 − 427 =
37. 37.800 − 497 =
38. 38.591 − 488 =
39. 39.387 − 299 =
40. 40.899 − 697 =

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