Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 164 · 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. 1.528 − 499 =
2. 2.598 − 519 =
3. 3.414 − 298 =
4. 4.972 − 698 =
5. 5.700 − 599 =
6. 6.996 − 399 =
7. 7.807 − 539 =
8. 8.547 − 417 =
9. 9.947 − 588 =
10. 10.789 − 597 =
11. 11.965 − 128 =
12. 12.928 − 798 =
13. 13.516 − 229 =
14. 14.719 − 488 =
15. 15.946 − 798 =
16. 16.831 − 118 =
17. 17.863 − 397 =
18. 18.734 − 339 =
19. 19.872 − 697 =
20. 20.736 − 697 =
21. 21.662 − 398 =
22. 22.910 − 498 =
23. 23.967 − 799 =
24. 24.936 − 297 =
25. 25.745 − 407 =
26. 26.394 − 328 =
27. 27.496 − 339 =
28. 28.723 − 589 =
29. 29.774 − 288 =
30. 30.779 − 138 =
31. 31.629 − 399 =
32. 32.524 − 498 =
33. 33.305 − 229 =
34. 34.733 − 698 =
35. 35.943 − 397 =
36. 36.611 − 497 =
37. 37.988 − 797 =
38. 38.891 − 497 =
39. 39.899 − 399 =
40. 40.923 − 698 =

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