3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 474 · 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. 1.510 + 192 =
2. 2.834 − 701 =
3. 3.640 + 545 =
4. 4.672 − 493 =
5. 5.675 − 474 =
6. 6.834 − 537 =
7. 7.741 − 133 =
8. 8.764 − 112 =
9. 9.565 − 143 =
10. 10.487 − 334 =
11. 11.497 − 385 =
12. 12.556 + 245 =
13. 13.785 − 202 =
14. 14.185 + 265 =
15. 15.370 + 468 =
16. 16.590 − 377 =
17. 17.239 + 599 =
18. 18.736 − 179 =
19. 19.740 − 218 =
20. 20.824 − 478 =
21. 21.630 + 186 =
22. 22.525 − 347 =
23. 23.550 + 571 =
24. 24.897 − 429 =
25. 25.698 − 114 =
26. 26.586 − 171 =
27. 27.527 + 468 =
28. 28.479 − 262 =
29. 29.424 − 135 =
30. 30.765 − 173 =
31. 31.508 − 342 =
32. 32.484 + 566 =
33. 33.370 + 431 =
34. 34.505 + 246 =
35. 35.703 − 494 =
36. 36.368 + 598 =
37. 37.192 + 319 =
38. 38.486 − 183 =
39. 39.527 + 222 =
40. 40.123 + 521 =

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