Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 604 · 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. 1.875 − 799 =
2. 2.521 − 199 =
3. 3.814 − 429 =
4. 4.650 − 199 =
5. 5.434 − 277 =
6. 6.325 − 297 =
7. 7.774 − 198 =
8. 8.947 − 298 =
9. 9.872 − 798 =
10. 10.566 − 369 =
11. 11.711 − 497 =
12. 12.946 − 697 =
13. 13.960 − 797 =
14. 14.671 − 639 =
15. 15.981 − 138 =
16. 16.972 − 699 =
17. 17.864 − 698 =
18. 18.947 − 398 =
19. 19.419 − 199 =
20. 20.542 − 498 =
21. 21.527 − 357 =
22. 22.704 − 689 =
23. 23.316 − 298 =
24. 24.510 − 299 =
25. 25.824 − 209 =
26. 26.642 − 447 =
27. 27.658 − 399 =
28. 28.886 − 597 =
29. 29.811 − 609 =
30. 30.644 − 219 =
31. 31.513 − 288 =
32. 32.454 − 417 =
33. 33.577 − 398 =
34. 34.433 − 267 =
35. 35.355 − 297 =
36. 36.944 − 197 =
37. 37.394 − 238 =
38. 38.868 − 598 =
39. 39.837 − 598 =
40. 40.935 − 289 =

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