Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 476 · 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. 1.621 − 578 =
2. 2.886 − 797 =
3. 3.738 − 159 =
4. 4.853 − 128 =
5. 5.265 − 179 =
6. 6.744 − 699 =
7. 7.866 − 798 =
8. 8.353 − 297 =
9. 9.825 − 498 =
10. 10.321 − 199 =
11. 11.867 − 198 =
12. 12.920 − 598 =
13. 13.419 − 168 =
14. 14.658 − 397 =
15. 15.392 − 199 =
16. 16.798 − 407 =
17. 17.531 − 398 =
18. 18.257 − 139 =
19. 19.780 − 687 =
20. 20.920 − 318 =
21. 21.937 − 279 =
22. 22.608 − 528 =
23. 23.702 − 497 =
24. 24.854 − 798 =
25. 25.788 − 598 =
26. 26.681 − 379 =
27. 27.584 − 528 =
28. 28.475 − 299 =
29. 29.502 − 178 =
30. 30.723 − 488 =
31. 31.590 − 429 =
32. 32.917 − 199 =
33. 33.343 − 197 =
34. 34.974 − 378 =
35. 35.588 − 469 =
36. 36.555 − 528 =
37. 37.853 − 797 =
38. 38.693 − 597 =
39. 39.834 − 628 =
40. 40.961 − 397 =

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