3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 983 · 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. 1.215 + 401 =
2. 2.589 + 449 =
3. 3.982 − 683 =
4. 4.581 + 572 =
5. 5.196 + 366 =
6. 6.504 + 165 =
7. 7.654 + 444 =
8. 8.457 − 126 =
9. 9.436 − 273 =
10. 10.266 + 536 =
11. 11.680 − 205 =
12. 12.378 + 225 =
13. 13.898 − 449 =
14. 14.264 + 373 =
15. 15.387 + 424 =
16. 16.563 − 297 =
17. 17.737 − 588 =
18. 18.773 − 431 =
19. 19.380 + 491 =
20. 20.612 − 179 =
21. 21.673 − 282 =
22. 22.620 + 522 =
23. 23.628 − 419 =
24. 24.987 − 776 =
25. 25.616 − 407 =
26. 26.549 + 148 =
27. 27.915 − 708 =
28. 28.512 − 123 =
29. 29.296 + 509 =
30. 30.498 − 208 =
31. 31.452 − 134 =
32. 32.372 + 538 =
33. 33.766 + 547 =
34. 34.652 + 581 =
35. 35.251 + 518 =
36. 36.617 + 526 =
37. 37.459 − 136 =
38. 38.283 + 681 =
39. 39.683 + 674 =
40. 40.591 − 421 =

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