3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 284 · 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. 1.864 − 603 =
2. 2.419 + 643 =
3. 3.659 − 516 =
4. 4.596 − 141 =
5. 5.680 + 543 =
6. 6.421 − 123 =
7. 7.634 + 195 =
8. 8.519 − 337 =
9. 9.142 + 658 =
10. 10.580 − 161 =
11. 11.553 − 256 =
12. 12.774 + 675 =
13. 13.805 − 282 =
14. 14.140 + 488 =
15. 15.634 + 403 =
16. 16.777 + 671 =
17. 17.518 − 232 =
18. 18.737 − 388 =
19. 19.774 + 526 =
20. 20.437 − 121 =
21. 21.432 + 636 =
22. 22.788 − 128 =
23. 23.361 + 547 =
24. 24.687 − 369 =
25. 25.555 − 148 =
26. 26.721 − 256 =
27. 27.538 + 344 =
28. 28.660 + 641 =
29. 29.208 + 328 =
30. 30.696 − 447 =
31. 31.770 − 246 =
32. 32.697 − 394 =
33. 33.417 − 159 =
34. 34.457 − 117 =
35. 35.481 + 477 =
36. 36.686 − 157 =
37. 37.467 + 242 =
38. 38.929 − 239 =
39. 39.689 + 421 =
40. 40.871 − 393 =

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