Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 517 · 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. 1.949 − 799 =
2. 2.873 − 797 =
3. 3.560 − 209 =
4. 4.795 − 519 =
5. 5.968 − 207 =
6. 6.371 − 198 =
7. 7.983 − 298 =
8. 8.846 − 797 =
9. 9.533 − 259 =
10. 10.901 − 797 =
11. 11.838 − 798 =
12. 12.486 − 398 =
13. 13.793 − 297 =
14. 14.979 − 197 =
15. 15.746 − 597 =
16. 16.736 − 227 =
17. 17.843 − 697 =
18. 18.751 − 397 =
19. 19.823 − 797 =
20. 20.610 − 449 =
21. 21.808 − 379 =
22. 22.704 − 668 =
23. 23.838 − 497 =
24. 24.942 − 199 =
25. 25.639 − 388 =
26. 26.913 − 439 =
27. 27.962 − 799 =
28. 28.906 − 628 =
29. 29.414 − 359 =
30. 30.822 − 487 =
31. 31.928 − 298 =
32. 32.545 − 429 =
33. 33.899 − 598 =
34. 34.849 − 799 =
35. 35.453 − 158 =
36. 36.460 − 297 =
37. 37.411 − 137 =
38. 38.607 − 399 =
39. 39.893 − 497 =
40. 40.967 − 298 =

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