Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 832 · 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. 1.278 − 198 =
2. 2.582 − 497 =
3. 3.961 − 578 =
4. 4.457 − 397 =
5. 5.676 − 329 =
6. 6.715 − 288 =
7. 7.607 − 559 =
8. 8.987 − 299 =
9. 9.896 − 197 =
10. 10.506 − 299 =
11. 11.871 − 298 =
12. 12.676 − 597 =
13. 13.818 − 458 =
14. 14.807 − 558 =
15. 15.872 − 698 =
16. 16.325 − 148 =
17. 17.884 − 267 =
18. 18.530 − 199 =
19. 19.658 − 149 =
20. 20.890 − 599 =
21. 21.823 − 797 =
22. 22.658 − 588 =
23. 23.978 − 398 =
24. 24.747 − 699 =
25. 25.941 − 167 =
26. 26.349 − 149 =
27. 27.710 − 598 =
28. 28.683 − 229 =
29. 29.707 − 158 =
30. 30.761 − 497 =
31. 31.876 − 699 =
32. 32.712 − 499 =
33. 33.700 − 399 =
34. 34.662 − 397 =
35. 35.982 − 199 =
36. 36.685 − 597 =
37. 37.806 − 297 =
38. 38.543 − 299 =
39. 39.286 − 198 =
40. 40.972 − 297 =

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