3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 955 · 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. 1.355 + 269 =
2. 2.499 − 197 =
3. 3.347 + 254 =
4. 4.174 + 141 =
5. 5.895 − 579 =
6. 6.771 + 652 =
7. 7.741 − 383 =
8. 8.514 − 371 =
9. 9.159 + 297 =
10. 10.231 + 389 =
11. 11.845 − 685 =
12. 12.673 − 249 =
13. 13.728 + 189 =
14. 14.714 + 194 =
15. 15.491 + 365 =
16. 16.484 − 328 =
17. 17.838 − 118 =
18. 18.417 + 371 =
19. 19.140 + 373 =
20. 20.552 − 191 =
21. 21.695 + 272 =
22. 22.551 + 616 =
23. 23.555 + 563 =
24. 24.606 − 231 =
25. 25.572 + 118 =
26. 26.858 − 729 =
27. 27.604 − 298 =
28. 28.617 − 321 =
29. 29.466 + 213 =
30. 30.489 − 123 =
31. 31.307 + 302 =
32. 32.723 + 639 =
33. 33.822 − 305 =
34. 34.612 − 309 =
35. 35.615 − 131 =
36. 36.764 + 508 =
37. 37.629 − 128 =
38. 38.714 − 344 =
39. 39.576 − 401 =
40. 40.150 + 327 =

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