3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 18 · 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. 1.522 + 463 =
2. 2.542 − 329 =
3. 3.668 + 305 =
4. 4.488 + 524 =
5. 5.774 + 264 =
6. 6.578 − 351 =
7. 7.752 + 556 =
8. 8.848 − 432 =
9. 9.896 − 647 =
10. 10.321 + 447 =
11. 11.548 − 168 =
12. 12.929 − 171 =
13. 13.437 + 279 =
14. 14.784 + 362 =
15. 15.938 − 649 =
16. 16.796 − 632 =
17. 17.452 + 639 =
18. 18.703 + 232 =
19. 19.819 − 603 =
20. 20.966 − 211 =
21. 21.541 − 256 =
22. 22.520 + 131 =
23. 23.890 − 723 =
24. 24.750 + 487 =
25. 25.530 − 171 =
26. 26.844 − 632 =
27. 27.870 − 721 =
28. 28.588 + 181 =
29. 29.847 − 192 =
30. 30.621 + 651 =
31. 31.602 − 344 =
32. 32.573 − 462 =
33. 33.548 + 381 =
34. 34.555 − 435 =
35. 35.348 + 227 =
36. 36.681 + 501 =
37. 37.384 + 631 =
38. 38.963 − 418 =
39. 39.491 − 181 =
40. 40.603 − 365 =

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