Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 955 · 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. 1.728 − 689 =
2. 2.960 − 329 =
3. 3.898 − 797 =
4. 4.984 − 197 =
5. 5.812 − 798 =
6. 6.817 − 648 =
7. 7.898 − 608 =
8. 8.874 − 697 =
9. 9.814 − 687 =
10. 10.588 − 269 =
11. 11.668 − 407 =
12. 12.997 − 599 =
13. 13.532 − 429 =
14. 14.861 − 699 =
15. 15.978 − 798 =
16. 16.740 − 327 =
17. 17.784 − 197 =
18. 18.575 − 497 =
19. 19.689 − 599 =
20. 20.613 − 258 =
21. 21.949 − 437 =
22. 22.843 − 497 =
23. 23.474 − 399 =
24. 24.976 − 229 =
25. 25.554 − 509 =
26. 26.816 − 599 =
27. 27.554 − 447 =
28. 28.949 − 648 =
29. 29.846 − 397 =
30. 30.244 − 199 =
31. 31.989 − 408 =
32. 32.647 − 298 =
33. 33.832 − 597 =
34. 34.648 − 629 =
35. 35.542 − 457 =
36. 36.996 − 599 =
37. 37.973 − 549 =
38. 38.970 − 497 =
39. 39.337 − 209 =
40. 40.936 − 499 =

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