Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 158 · 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. 1.688 − 597 =
2. 2.800 − 698 =
3. 3.881 − 289 =
4. 4.901 − 669 =
5. 5.942 − 437 =
6. 6.509 − 197 =
7. 7.821 − 698 =
8. 8.700 − 498 =
9. 9.667 − 618 =
10. 10.431 − 297 =
11. 11.781 − 557 =
12. 12.938 − 328 =
13. 13.346 − 268 =
14. 14.479 − 299 =
15. 15.882 − 397 =
16. 16.467 − 169 =
17. 17.924 − 148 =
18. 18.863 − 399 =
19. 19.881 − 798 =
20. 20.692 − 338 =
21. 21.533 − 497 =
22. 22.771 − 399 =
23. 23.895 − 289 =
24. 24.551 − 397 =
25. 25.402 − 198 =
26. 26.869 − 439 =
27. 27.741 − 499 =
28. 28.347 − 199 =
29. 29.774 − 697 =
30. 30.254 − 199 =
31. 31.693 − 638 =
32. 32.896 − 137 =
33. 33.695 − 458 =
34. 34.941 − 399 =
35. 35.803 − 498 =
36. 36.669 − 429 =
37. 37.956 − 697 =
38. 38.830 − 799 =
39. 39.615 − 128 =
40. 40.694 − 648 =

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