3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 720 · 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. 1.678 − 383 =
2. 2.840 − 349 =
3. 3.683 − 393 =
4. 4.907 − 767 =
5. 5.387 + 137 =
6. 6.830 − 648 =
7. 7.316 + 139 =
8. 8.528 − 375 =
9. 9.899 − 197 =
10. 10.623 − 176 =
11. 11.969 − 285 =
12. 12.580 − 233 =
13. 13.485 − 135 =
14. 14.503 − 143 =
15. 15.678 − 314 =
16. 16.125 + 121 =
17. 17.753 + 315 =
18. 18.426 + 581 =
19. 19.726 − 252 =
20. 20.155 + 491 =
21. 21.304 + 265 =
22. 22.843 − 178 =
23. 23.644 − 327 =
24. 24.287 + 342 =
25. 25.569 + 515 =
26. 26.287 + 573 =
27. 27.588 + 163 =
28. 28.781 + 132 =
29. 29.590 + 487 =
30. 30.531 + 188 =
31. 31.173 + 281 =
32. 32.754 − 271 =
33. 33.282 + 624 =
34. 34.729 + 112 =
35. 35.596 + 607 =
36. 36.518 + 621 =
37. 37.640 − 166 =
38. 38.614 − 466 =
39. 39.935 − 185 =
40. 40.977 − 174 =

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