3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 710 · 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. 1.132 + 367 =
2. 2.708 − 374 =
3. 3.602 − 154 =
4. 4.522 + 546 =
5. 5.562 − 386 =
6. 6.780 − 437 =
7. 7.297 + 279 =
8. 8.360 + 653 =
9. 9.717 − 296 =
10. 10.424 − 268 =
11. 11.746 + 357 =
12. 12.820 − 526 =
13. 13.153 + 249 =
14. 14.617 − 371 =
15. 15.265 + 243 =
16. 16.648 − 151 =
17. 17.594 − 214 =
18. 18.609 + 251 =
19. 19.125 + 487 =
20. 20.442 + 426 =
21. 21.426 + 554 =
22. 22.547 − 201 =
23. 23.784 − 581 =
24. 24.703 − 233 =
25. 25.708 − 606 =
26. 26.518 + 531 =
27. 27.519 + 661 =
28. 28.754 + 195 =
29. 29.952 − 794 =
30. 30.684 − 523 =
31. 31.812 − 268 =
32. 32.700 − 227 =
33. 33.158 + 255 =
34. 34.569 − 408 =
35. 35.672 + 331 =
36. 36.359 + 664 =
37. 37.623 + 181 =
38. 38.560 − 382 =
39. 39.512 + 255 =
40. 40.155 + 617 =

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