Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 594 · 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. 1.807 − 447 =
2. 2.547 − 419 =
3. 3.891 − 597 =
4. 4.832 − 697 =
5. 5.426 − 378 =
6. 6.509 − 247 =
7. 7.293 − 197 =
8. 8.890 − 679 =
9. 9.575 − 549 =
10. 10.944 − 699 =
11. 11.673 − 398 =
12. 12.230 − 198 =
13. 13.926 − 297 =
14. 14.664 − 577 =
15. 15.847 − 559 =
16. 16.810 − 699 =
17. 17.689 − 459 =
18. 18.834 − 798 =
19. 19.959 − 647 =
20. 20.804 − 607 =
21. 21.465 − 399 =
22. 22.548 − 198 =
23. 23.985 − 298 =
24. 24.656 − 148 =
25. 25.969 − 498 =
26. 26.983 − 699 =
27. 27.639 − 478 =
28. 28.597 − 558 =
29. 29.429 − 297 =
30. 30.935 − 798 =
31. 31.367 − 258 =
32. 32.384 − 279 =
33. 33.721 − 197 =
34. 34.994 − 599 =
35. 35.733 − 347 =
36. 36.992 − 499 =
37. 37.363 − 199 =
38. 38.733 − 528 =
39. 39.287 − 199 =
40. 40.818 − 498 =

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