Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 468 · 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. 1.779 − 208 =
2. 2.824 − 199 =
3. 3.870 − 397 =
4. 4.682 − 498 =
5. 5.745 − 497 =
6. 6.802 − 397 =
7. 7.381 − 197 =
8. 8.574 − 189 =
9. 9.479 − 269 =
10. 10.693 − 298 =
11. 11.445 − 178 =
12. 12.557 − 329 =
13. 13.858 − 409 =
14. 14.237 − 198 =
15. 15.918 − 597 =
16. 16.616 − 298 =
17. 17.372 − 299 =
18. 18.965 − 657 =
19. 19.942 − 307 =
20. 20.900 − 298 =
21. 21.577 − 297 =
22. 22.709 − 299 =
23. 23.737 − 669 =
24. 24.755 − 697 =
25. 25.869 − 389 =
26. 26.498 − 299 =
27. 27.763 − 388 =
28. 28.518 − 197 =
29. 29.827 − 497 =
30. 30.692 − 159 =
31. 31.468 − 208 =
32. 32.673 − 197 =
33. 33.692 − 579 =
34. 34.729 − 558 =
35. 35.317 − 299 =
36. 36.526 − 457 =
37. 37.630 − 459 =
38. 38.769 − 399 =
39. 39.726 − 497 =
40. 40.780 − 298 =

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