3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 69 · 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. 1.519 − 392 =
2. 2.907 − 378 =
3. 3.503 + 165 =
4. 4.721 + 308 =
5. 5.592 − 323 =
6. 6.454 + 641 =
7. 7.604 + 194 =
8. 8.179 + 168 =
9. 9.939 − 779 =
10. 10.703 − 562 =
11. 11.632 + 272 =
12. 12.353 + 207 =
13. 13.224 + 512 =
14. 14.490 − 193 =
15. 15.553 − 366 =
16. 16.666 − 506 =
17. 17.728 − 531 =
18. 18.517 + 632 =
19. 19.523 + 273 =
20. 20.649 + 232 =
21. 21.452 + 392 =
22. 22.910 − 262 =
23. 23.522 − 345 =
24. 24.245 + 467 =
25. 25.887 − 166 =
26. 26.658 − 456 =
27. 27.193 + 642 =
28. 28.837 − 268 =
29. 29.430 + 114 =
30. 30.563 + 531 =
31. 31.556 − 385 =
32. 32.435 − 293 =
33. 33.453 − 174 =
34. 34.256 + 204 =
35. 35.716 − 428 =
36. 36.510 + 638 =
37. 37.207 + 295 =
38. 38.685 − 363 =
39. 39.826 − 661 =
40. 40.443 − 125 =

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