3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 565 · 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. 1.620 + 171 =
2. 2.529 − 166 =
3. 3.393 + 226 =
4. 4.698 + 618 =
5. 5.626 + 472 =
6. 6.684 + 176 =
7. 7.653 − 551 =
8. 8.311 + 381 =
9. 9.464 − 223 =
10. 10.492 + 666 =
11. 11.562 + 683 =
12. 12.614 − 384 =
13. 13.675 − 208 =
14. 14.728 + 192 =
15. 15.589 − 342 =
16. 16.470 − 324 =
17. 17.437 − 162 =
18. 18.678 − 304 =
19. 19.158 + 277 =
20. 20.759 − 561 =
21. 21.292 + 592 =
22. 22.498 + 627 =
23. 23.549 − 117 =
24. 24.619 − 404 =
25. 25.482 + 274 =
26. 26.667 + 344 =
27. 27.337 + 534 =
28. 28.163 + 246 =
29. 29.233 + 146 =
30. 30.406 + 468 =
31. 31.555 − 339 =
32. 32.175 + 557 =
33. 33.951 − 562 =
34. 34.481 − 122 =
35. 35.127 + 601 =
36. 36.157 + 396 =
37. 37.422 − 189 =
38. 38.554 − 409 =
39. 39.546 + 575 =
40. 40.795 − 304 =

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