3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 840 · 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. 1.761 − 587 =
2. 2.680 − 255 =
3. 3.628 + 476 =
4. 4.842 − 154 =
5. 5.202 + 556 =
6. 6.829 − 554 =
7. 7.773 − 129 =
8. 8.439 + 549 =
9. 9.253 + 503 =
10. 10.357 + 651 =
11. 11.451 − 296 =
12. 12.522 + 689 =
13. 13.186 + 157 =
14. 14.509 − 241 =
15. 15.413 − 113 =
16. 16.704 + 293 =
17. 17.776 − 136 =
18. 18.165 + 117 =
19. 19.174 + 386 =
20. 20.703 + 345 =
21. 21.361 + 368 =
22. 22.928 − 537 =
23. 23.725 − 278 =
24. 24.451 + 473 =
25. 25.459 − 296 =
26. 26.778 − 551 =
27. 27.513 + 573 =
28. 28.719 + 402 =
29. 29.627 − 268 =
30. 30.401 + 514 =
31. 31.274 + 496 =
32. 32.927 − 401 =
33. 33.415 − 266 =
34. 34.462 + 274 =
35. 35.840 − 655 =
36. 36.854 − 184 =
37. 37.182 + 158 =
38. 38.548 − 168 =
39. 39.650 − 185 =
40. 40.667 − 321 =

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