3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 32 · 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. 1.141 + 158 =
2. 2.357 + 635 =
3. 3.425 + 197 =
4. 4.533 + 459 =
5. 5.707 + 377 =
6. 6.720 − 169 =
7. 7.407 + 112 =
8. 8.459 + 634 =
9. 9.778 + 279 =
10. 10.300 + 266 =
11. 11.502 + 686 =
12. 12.737 + 303 =
13. 13.302 + 625 =
14. 14.470 − 128 =
15. 15.363 + 329 =
16. 16.476 + 302 =
17. 17.847 − 248 =
18. 18.554 + 213 =
19. 19.609 − 151 =
20. 20.927 − 211 =
21. 21.140 + 591 =
22. 22.416 − 311 =
23. 23.712 + 282 =
24. 24.563 + 258 =
25. 25.739 − 212 =
26. 26.418 + 613 =
27. 27.550 − 389 =
28. 28.974 − 834 =
29. 29.729 − 218 =
30. 30.546 − 164 =
31. 31.260 + 571 =
32. 32.698 − 158 =
33. 33.978 − 538 =
34. 34.722 + 185 =
35. 35.447 − 131 =
36. 36.760 − 301 =
37. 37.936 − 159 =
38. 38.790 − 221 =
39. 39.772 + 499 =
40. 40.762 − 363 =

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