3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 686 · 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. 1.434 + 524 =
2. 2.437 + 236 =
3. 3.889 − 787 =
4. 4.940 − 224 =
5. 5.721 − 196 =
6. 6.439 − 141 =
7. 7.238 + 246 =
8. 8.831 − 302 =
9. 9.289 + 354 =
10. 10.807 − 398 =
11. 11.895 − 469 =
12. 12.652 − 384 =
13. 13.897 − 699 =
14. 14.641 − 265 =
15. 15.411 + 222 =
16. 16.252 + 186 =
17. 17.638 − 384 =
18. 18.740 + 323 =
19. 19.635 − 469 =
20. 20.219 + 425 =
21. 21.643 + 454 =
22. 22.595 + 534 =
23. 23.208 + 551 =
24. 24.766 − 581 =
25. 25.692 + 658 =
26. 26.652 + 571 =
27. 27.985 − 605 =
28. 28.824 − 681 =
29. 29.947 − 134 =
30. 30.734 + 635 =
31. 31.890 − 637 =
32. 32.574 + 413 =
33. 33.296 + 145 =
34. 34.895 − 376 =
35. 35.317 + 311 =
36. 36.450 + 491 =
37. 37.434 + 137 =
38. 38.538 − 132 =
39. 39.507 − 291 =
40. 40.718 − 174 =

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