Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 345 · 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. 1.463 − 259 =
2. 2.379 − 269 =
3. 3.925 − 297 =
4. 4.929 − 148 =
5. 5.814 − 679 =
6. 6.851 − 459 =
7. 7.399 − 198 =
8. 8.934 − 598 =
9. 9.939 − 498 =
10. 10.802 − 599 =
11. 11.907 − 148 =
12. 12.840 − 299 =
13. 13.546 − 198 =
14. 14.644 − 609 =
15. 15.964 − 609 =
16. 16.445 − 238 =
17. 17.920 − 657 =
18. 18.865 − 799 =
19. 19.868 − 397 =
20. 20.857 − 227 =
21. 21.711 − 199 =
22. 22.952 − 699 =
23. 23.995 − 627 =
24. 24.917 − 238 =
25. 25.956 − 497 =
26. 26.641 − 617 =
27. 27.798 − 397 =
28. 28.337 − 178 =
29. 29.848 − 317 =
30. 30.624 − 589 =
31. 31.569 − 498 =
32. 32.355 − 248 =
33. 33.333 − 299 =
34. 34.392 − 198 =
35. 35.688 − 428 =
36. 36.975 − 798 =
37. 37.328 − 197 =
38. 38.704 − 299 =
39. 39.465 − 397 =
40. 40.916 − 799 =

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