3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 313 · 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. 1.412 − 141 =
2. 2.881 − 664 =
3. 3.145 + 645 =
4. 4.714 + 257 =
5. 5.431 − 291 =
6. 6.751 − 341 =
7. 7.747 + 161 =
8. 8.588 − 395 =
9. 9.137 + 136 =
10. 10.587 + 377 =
11. 11.157 + 196 =
12. 12.497 + 117 =
13. 13.588 + 601 =
14. 14.522 − 141 =
15. 15.590 + 256 =
16. 16.511 − 181 =
17. 17.617 − 118 =
18. 18.575 + 185 =
19. 19.640 − 348 =
20. 20.581 − 454 =
21. 21.283 + 292 =
22. 22.574 − 384 =
23. 23.423 − 289 =
24. 24.552 − 223 =
25. 25.471 − 231 =
26. 26.294 + 208 =
27. 27.899 − 129 =
28. 28.533 − 354 =
29. 29.452 − 151 =
30. 30.949 − 117 =
31. 31.448 − 321 =
32. 32.759 − 572 =
33. 33.783 − 145 =
34. 34.413 + 141 =
35. 35.725 + 461 =
36. 36.244 + 352 =
37. 37.649 − 484 =
38. 38.972 − 669 =
39. 39.428 − 184 =
40. 40.784 − 139 =

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