Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 645 · 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. 1.849 − 598 =
2. 2.944 − 598 =
3. 3.712 − 338 =
4. 4.808 − 299 =
5. 5.723 − 398 =
6. 6.945 − 207 =
7. 7.369 − 148 =
8. 8.963 − 599 =
9. 9.905 − 697 =
10. 10.192 − 148 =
11. 11.509 − 298 =
12. 12.751 − 527 =
13. 13.942 − 627 =
14. 14.250 − 229 =
15. 15.836 − 597 =
16. 16.860 − 427 =
17. 17.821 − 468 =
18. 18.597 − 279 =
19. 19.687 − 557 =
20. 20.678 − 529 =
21. 21.726 − 699 =
22. 22.674 − 197 =
23. 23.654 − 617 =
24. 24.755 − 698 =
25. 25.702 − 497 =
26. 26.505 − 197 =
27. 27.519 − 208 =
28. 28.456 − 439 =
29. 29.823 − 679 =
30. 30.576 − 438 =
31. 31.523 − 397 =
32. 32.730 − 629 =
33. 33.539 − 499 =
34. 34.962 − 249 =
35. 35.632 − 599 =
36. 36.756 − 299 =
37. 37.767 − 297 =
38. 38.208 − 127 =
39. 39.834 − 407 =
40. 40.985 − 797 =

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