3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 564 · 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. 1.742 − 578 =
2. 2.279 + 445 =
3. 3.557 + 284 =
4. 4.440 − 315 =
5. 5.593 − 481 =
6. 6.658 + 439 =
7. 7.648 + 689 =
8. 8.382 + 679 =
9. 9.185 + 529 =
10. 10.586 + 258 =
11. 11.784 + 224 =
12. 12.417 − 171 =
13. 13.614 − 373 =
14. 14.735 − 231 =
15. 15.716 − 507 =
16. 16.441 + 159 =
17. 17.709 − 123 =
18. 18.417 + 505 =
19. 19.383 + 263 =
20. 20.425 − 255 =
21. 21.628 − 143 =
22. 22.431 − 165 =
23. 23.636 + 671 =
24. 24.538 + 265 =
25. 25.860 − 133 =
26. 26.658 + 141 =
27. 27.499 − 211 =
28. 28.219 + 467 =
29. 29.665 + 499 =
30. 30.413 + 674 =
31. 31.929 − 728 =
32. 32.317 + 119 =
33. 33.967 − 706 =
34. 34.817 − 267 =
35. 35.737 − 637 =
36. 36.726 + 151 =
37. 37.482 − 263 =
38. 38.412 + 311 =
39. 39.626 − 401 =
40. 40.538 − 143 =

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