Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 897 · 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. 1.784 − 599 =
2. 2.668 − 298 =
3. 3.411 − 319 =
4. 4.197 − 148 =
5. 5.467 − 278 =
6. 6.580 − 507 =
7. 7.582 − 399 =
8. 8.835 − 359 =
9. 9.954 − 797 =
10. 10.608 − 199 =
11. 11.993 − 499 =
12. 12.950 − 599 =
13. 13.617 − 598 =
14. 14.813 − 297 =
15. 15.441 − 339 =
16. 16.567 − 497 =
17. 17.463 − 219 =
18. 18.576 − 299 =
19. 19.626 − 199 =
20. 20.503 − 397 =
21. 21.924 − 609 =
22. 22.472 − 299 =
23. 23.970 − 698 =
24. 24.940 − 358 =
25. 25.820 − 697 =
26. 26.604 − 238 =
27. 27.880 − 598 =
28. 28.878 − 628 =
29. 29.218 − 197 =
30. 30.688 − 128 =
31. 31.592 − 487 =
32. 32.773 − 698 =
33. 33.483 − 237 =
34. 34.893 − 799 =
35. 35.901 − 798 =
36. 36.990 − 307 =
37. 37.857 − 799 =
38. 38.842 − 799 =
39. 39.711 − 677 =
40. 40.889 − 458 =

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