3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 614 · 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. 1.144 + 287 =
2. 2.642 + 175 =
3. 3.243 + 128 =
4. 4.735 − 188 =
5. 5.885 − 451 =
6. 6.729 + 452 =
7. 7.142 + 391 =
8. 8.699 + 144 =
9. 9.143 + 187 =
10. 10.551 + 506 =
11. 11.588 − 126 =
12. 12.719 + 264 =
13. 13.494 + 511 =
14. 14.707 + 112 =
15. 15.729 + 457 =
16. 16.604 − 472 =
17. 17.621 − 263 =
18. 18.861 − 454 =
19. 19.814 − 122 =
20. 20.972 − 817 =
21. 21.889 − 244 =
22. 22.694 − 223 =
23. 23.494 + 322 =
24. 24.283 + 336 =
25. 25.625 + 411 =
26. 26.559 − 115 =
27. 27.478 − 133 =
28. 28.141 + 347 =
29. 29.580 − 214 =
30. 30.611 + 185 =
31. 31.194 + 125 =
32. 32.622 − 311 =
33. 33.152 + 634 =
34. 34.629 − 404 =
35. 35.318 + 472 =
36. 36.127 + 414 =
37. 37.860 − 251 =
38. 38.459 − 137 =
39. 39.882 − 152 =
40. 40.874 − 674 =

Free mental maths lessons, practice and worksheets at talentjr.in/mental-maths