Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 115 · 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. 1.701 − 669 =
2. 2.933 − 499 =
3. 3.450 − 197 =
4. 4.795 − 437 =
5. 5.785 − 189 =
6. 6.659 − 599 =
7. 7.964 − 509 =
8. 8.960 − 208 =
9. 9.752 − 428 =
10. 10.578 − 498 =
11. 11.413 − 357 =
12. 12.699 − 379 =
13. 13.726 − 118 =
14. 14.936 − 578 =
15. 15.834 − 288 =
16. 16.390 − 247 =
17. 17.949 − 589 =
18. 18.844 − 498 =
19. 19.434 − 398 =
20. 20.838 − 699 =
21. 21.589 − 157 =
22. 22.813 − 498 =
23. 23.891 − 598 =
24. 24.564 − 399 =
25. 25.625 − 599 =
26. 26.618 − 559 =
27. 27.703 − 297 =
28. 28.571 − 369 =
29. 29.979 − 259 =
30. 30.861 − 798 =
31. 31.457 − 269 =
32. 32.298 − 198 =
33. 33.239 − 148 =
34. 34.499 − 198 =
35. 35.863 − 557 =
36. 36.660 − 577 =
37. 37.818 − 799 =
38. 38.978 − 299 =
39. 39.841 − 797 =
40. 40.618 − 517 =

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