3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 662 · 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. 1.228 + 676 =
2. 2.954 − 411 =
3. 3.629 + 625 =
4. 4.982 − 728 =
5. 5.783 + 466 =
6. 6.175 + 243 =
7. 7.765 − 409 =
8. 8.523 + 173 =
9. 9.194 + 189 =
10. 10.598 + 278 =
11. 11.433 − 207 =
12. 12.506 − 135 =
13. 13.873 − 305 =
14. 14.263 + 319 =
15. 15.879 − 522 =
16. 16.753 − 263 =
17. 17.791 − 384 =
18. 18.904 − 406 =
19. 19.456 + 164 =
20. 20.730 + 228 =
21. 21.875 − 476 =
22. 22.529 − 166 =
23. 23.509 + 616 =
24. 24.709 + 346 =
25. 25.811 − 158 =
26. 26.422 − 251 =
27. 27.652 − 207 =
28. 28.891 − 623 =
29. 29.440 − 194 =
30. 30.148 + 171 =
31. 31.291 + 253 =
32. 32.381 + 674 =
33. 33.472 + 351 =
34. 34.834 − 411 =
35. 35.835 − 168 =
36. 36.671 + 553 =
37. 37.490 + 607 =
38. 38.787 + 127 =
39. 39.176 + 406 =
40. 40.740 − 562 =

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