Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 372 · 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. 1.947 − 189 =
2. 2.548 − 199 =
3. 3.504 − 489 =
4. 4.263 − 149 =
5. 5.267 − 159 =
6. 6.613 − 399 =
7. 7.824 − 308 =
8. 8.440 − 197 =
9. 9.735 − 597 =
10. 10.890 − 799 =
11. 11.328 − 199 =
12. 12.648 − 499 =
13. 13.949 − 607 =
14. 14.484 − 297 =
15. 15.641 − 499 =
16. 16.734 − 697 =
17. 17.737 − 359 =
18. 18.734 − 398 =
19. 19.489 − 427 =
20. 20.319 − 199 =
21. 21.993 − 619 =
22. 22.382 − 298 =
23. 23.463 − 389 =
24. 24.956 − 579 =
25. 25.740 − 297 =
26. 26.386 − 297 =
27. 27.157 − 127 =
28. 28.826 − 497 =
29. 29.884 − 407 =
30. 30.922 − 199 =
31. 31.814 − 698 =
32. 32.367 − 297 =
33. 33.990 − 698 =
34. 34.707 − 648 =
35. 35.687 − 237 =
36. 36.864 − 597 =
37. 37.321 − 197 =
38. 38.794 − 617 =
39. 39.439 − 277 =
40. 40.932 − 798 =

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