3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 97 · 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. 1.256 + 303 =
2. 2.654 + 502 =
3. 3.404 + 464 =
4. 4.552 + 199 =
5. 5.646 − 411 =
6. 6.386 + 206 =
7. 7.510 − 134 =
8. 8.766 − 253 =
9. 9.421 + 356 =
10. 10.616 − 307 =
11. 11.940 − 306 =
12. 12.182 + 518 =
13. 13.454 − 118 =
14. 14.524 + 196 =
15. 15.355 + 574 =
16. 16.711 − 252 =
17. 17.647 − 282 =
18. 18.973 − 181 =
19. 19.786 − 191 =
20. 20.932 − 727 =
21. 21.560 + 624 =
22. 22.542 − 429 =
23. 23.785 + 598 =
24. 24.808 − 266 =
25. 25.818 − 597 =
26. 26.690 − 131 =
27. 27.333 + 141 =
28. 28.534 − 168 =
29. 29.874 − 554 =
30. 30.891 − 361 =
31. 31.766 + 273 =
32. 32.636 + 274 =
33. 33.163 + 484 =
34. 34.507 − 381 =
35. 35.360 + 173 =
36. 36.530 − 176 =
37. 37.534 − 352 =
38. 38.156 + 533 =
39. 39.459 − 217 =
40. 40.562 + 634 =

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