3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 646 · 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. 1.150 + 566 =
2. 2.491 + 234 =
3. 3.569 − 235 =
4. 4.927 − 148 =
5. 5.403 + 336 =
6. 6.306 + 193 =
7. 7.657 + 372 =
8. 8.743 − 476 =
9. 9.880 − 398 =
10. 10.886 − 196 =
11. 11.827 − 268 =
12. 12.544 − 168 =
13. 13.586 − 303 =
14. 14.720 − 417 =
15. 15.715 + 204 =
16. 16.787 + 544 =
17. 17.434 + 154 =
18. 18.456 + 631 =
19. 19.435 + 404 =
20. 20.822 − 438 =
21. 21.786 + 614 =
22. 22.686 + 153 =
23. 23.825 − 193 =
24. 24.156 + 525 =
25. 25.404 + 183 =
26. 26.486 − 161 =
27. 27.155 + 115 =
28. 28.408 + 421 =
29. 29.803 − 416 =
30. 30.610 + 431 =
31. 31.795 − 374 =
32. 32.590 − 386 =
33. 33.705 + 613 =
34. 34.187 + 375 =
35. 35.407 + 411 =
36. 36.442 − 141 =
37. 37.716 − 301 =
38. 38.679 + 158 =
39. 39.728 − 543 =
40. 40.510 − 231 =

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