3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 80 · 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. 1.629 + 631 =
2. 2.323 + 624 =
3. 3.649 + 155 =
4. 4.881 − 167 =
5. 5.980 − 318 =
6. 6.459 + 249 =
7. 7.432 − 226 =
8. 8.422 − 118 =
9. 9.516 − 414 =
10. 10.649 + 612 =
11. 11.557 + 129 =
12. 12.906 − 243 =
13. 13.273 + 269 =
14. 14.130 + 221 =
15. 15.825 − 601 =
16. 16.486 − 182 =
17. 17.488 − 154 =
18. 18.557 − 185 =
19. 19.655 − 184 =
20. 20.713 − 607 =
21. 21.715 + 439 =
22. 22.133 + 312 =
23. 23.171 + 641 =
24. 24.451 − 294 =
25. 25.646 + 685 =
26. 26.466 − 175 =
27. 27.419 + 144 =
28. 28.463 + 493 =
29. 29.476 − 224 =
30. 30.763 + 133 =
31. 31.779 + 652 =
32. 32.291 + 184 =
33. 33.545 − 128 =
34. 34.787 + 156 =
35. 35.973 − 281 =
36. 36.157 + 678 =
37. 37.629 − 453 =
38. 38.514 − 379 =
39. 39.338 + 438 =
40. 40.128 + 636 =

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