Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 798 · 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. 1.833 − 288 =
2. 2.331 − 198 =
3. 3.777 − 567 =
4. 4.692 − 598 =
5. 5.942 − 797 =
6. 6.582 − 558 =
7. 7.597 − 399 =
8. 8.433 − 398 =
9. 9.608 − 329 =
10. 10.913 − 198 =
11. 11.856 − 497 =
12. 12.777 − 698 =
13. 13.871 − 589 =
14. 14.848 − 658 =
15. 15.557 − 428 =
16. 16.527 − 498 =
17. 17.707 − 247 =
18. 18.858 − 798 =
19. 19.783 − 499 =
20. 20.905 − 257 =
21. 21.476 − 197 =
22. 22.793 − 298 =
23. 23.753 − 278 =
24. 24.430 − 398 =
25. 25.555 − 497 =
26. 26.671 − 557 =
27. 27.604 − 498 =
28. 28.560 − 399 =
29. 29.844 − 507 =
30. 30.492 − 189 =
31. 31.746 − 698 =
32. 32.903 − 399 =
33. 33.550 − 398 =
34. 34.747 − 197 =
35. 35.533 − 298 =
36. 36.474 − 297 =
37. 37.854 − 798 =
38. 38.948 − 198 =
39. 39.895 − 597 =
40. 40.578 − 129 =

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