Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 66 · 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. 1.993 − 477 =
2. 2.867 − 698 =
3. 3.581 − 397 =
4. 4.875 − 498 =
5. 5.556 − 517 =
6. 6.383 − 207 =
7. 7.624 − 499 =
8. 8.712 − 299 =
9. 9.829 − 519 =
10. 10.311 − 199 =
11. 11.768 − 219 =
12. 12.970 − 798 =
13. 13.838 − 309 =
14. 14.822 − 398 =
15. 15.990 − 167 =
16. 16.883 − 799 =
17. 17.768 − 557 =
18. 18.365 − 329 =
19. 19.178 − 157 =
20. 20.827 − 498 =
21. 21.545 − 139 =
22. 22.651 − 468 =
23. 23.740 − 199 =
24. 24.682 − 399 =
25. 25.613 − 238 =
26. 26.432 − 259 =
27. 27.963 − 198 =
28. 28.554 − 248 =
29. 29.671 − 397 =
30. 30.983 − 118 =
31. 31.343 − 199 =
32. 32.826 − 518 =
33. 33.667 − 398 =
34. 34.893 − 299 =
35. 35.821 − 799 =
36. 36.324 − 297 =
37. 37.453 − 418 =
38. 38.747 − 347 =
39. 39.472 − 199 =
40. 40.821 − 659 =

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