3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 939 · 40 questions

How to do it in your head (Hundreds first): Keep the first number as it is and split the second into hundreds, tens and ones. Add (or take away) the hundreds first, then the tens. Finish with the ones — bridge through a ten if you need to.

1. 1.678 − 224 =
2. 2.520 − 291 =
3. 3.464 + 428 =
4. 4.285 + 406 =
5. 5.813 − 274 =
6. 6.795 − 211 =
7. 7.472 − 256 =
8. 8.499 − 368 =
9. 9.435 + 204 =
10. 10.424 − 244 =
11. 11.192 + 626 =
12. 12.618 + 442 =
13. 13.710 + 638 =
14. 14.710 − 242 =
15. 15.437 + 288 =
16. 16.544 − 296 =
17. 17.528 + 403 =
18. 18.426 − 319 =
19. 19.127 + 339 =
20. 20.756 − 257 =
21. 21.705 − 267 =
22. 22.699 − 573 =
23. 23.687 − 426 =
24. 24.917 − 815 =
25. 25.592 + 629 =
26. 26.370 + 548 =
27. 27.251 + 142 =
28. 28.823 − 515 =
29. 29.690 + 162 =
30. 30.838 − 304 =
31. 31.862 − 671 =
32. 32.913 − 771 =
33. 33.638 − 251 =
34. 34.351 + 441 =
35. 35.655 + 121 =
36. 36.953 − 645 =
37. 37.882 − 129 =
38. 38.278 + 173 =
39. 39.619 + 556 =
40. 40.769 − 304 =

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