Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 72 · 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. 1.816 − 297 =
2. 2.961 − 698 =
3. 3.823 − 499 =
4. 4.933 − 797 =
5. 5.884 − 498 =
6. 6.715 − 397 =
7. 7.772 − 228 =
8. 8.524 − 138 =
9. 9.833 − 398 =
10. 10.929 − 498 =
11. 11.996 − 347 =
12. 12.564 − 297 =
13. 13.498 − 197 =
14. 14.742 − 637 =
15. 15.149 − 127 =
16. 16.935 − 797 =
17. 17.863 − 498 =
18. 18.505 − 268 =
19. 19.689 − 299 =
20. 20.325 − 128 =
21. 21.420 − 397 =
22. 22.618 − 428 =
23. 23.749 − 497 =
24. 24.521 − 479 =
25. 25.446 − 349 =
26. 26.574 − 549 =
27. 27.785 − 488 =
28. 28.942 − 589 =
29. 29.899 − 667 =
30. 30.271 − 149 =
31. 31.718 − 698 =
32. 32.691 − 199 =
33. 33.712 − 689 =
34. 34.550 − 498 =
35. 35.709 − 509 =
36. 36.884 − 529 =
37. 37.392 − 289 =
38. 38.968 − 698 =
39. 39.636 − 299 =
40. 40.616 − 579 =

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