Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 693 · 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. 1.867 − 699 =
2. 2.739 − 328 =
3. 3.871 − 378 =
4. 4.415 − 397 =
5. 5.922 − 798 =
6. 6.491 − 147 =
7. 7.641 − 299 =
8. 8.780 − 597 =
9. 9.906 − 669 =
10. 10.801 − 197 =
11. 11.785 − 528 =
12. 12.874 − 598 =
13. 13.641 − 208 =
14. 14.676 − 659 =
15. 15.713 − 699 =
16. 16.898 − 447 =
17. 17.721 − 378 =
18. 18.777 − 638 =
19. 19.619 − 497 =
20. 20.882 − 239 =
21. 21.922 − 599 =
22. 22.847 − 199 =
23. 23.598 − 279 =
24. 24.858 − 139 =
25. 25.823 − 598 =
26. 26.562 − 499 =
27. 27.990 − 639 =
28. 28.822 − 299 =
29. 29.806 − 569 =
30. 30.354 − 299 =
31. 31.957 − 547 =
32. 32.842 − 397 =
33. 33.452 − 397 =
34. 34.818 − 319 =
35. 35.477 − 437 =
36. 36.554 − 498 =
37. 37.399 − 369 =
38. 38.705 − 598 =
39. 39.921 − 429 =
40. 40.518 − 268 =

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