3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 161 · 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. 1.562 − 136 =
2. 2.725 + 288 =
3. 3.349 + 632 =
4. 4.544 − 426 =
5. 5.710 + 358 =
6. 6.801 − 532 =
7. 7.313 + 401 =
8. 8.497 − 175 =
9. 9.332 + 287 =
10. 10.436 − 172 =
11. 11.460 − 194 =
12. 12.429 − 114 =
13. 13.353 + 191 =
14. 14.604 − 172 =
15. 15.580 − 207 =
16. 16.557 − 268 =
17. 17.697 + 184 =
18. 18.403 + 478 =
19. 19.719 − 174 =
20. 20.874 − 294 =
21. 21.428 − 124 =
22. 22.685 + 207 =
23. 23.610 − 331 =
24. 24.685 + 648 =
25. 25.587 + 311 =
26. 26.242 + 152 =
27. 27.471 + 191 =
28. 28.467 + 293 =
29. 29.644 − 367 =
30. 30.693 + 196 =
31. 31.198 + 557 =
32. 32.548 + 207 =
33. 33.881 − 712 =
34. 34.611 + 551 =
35. 35.459 + 664 =
36. 36.192 + 208 =
37. 37.672 + 671 =
38. 38.714 − 463 =
39. 39.636 − 319 =
40. 40.638 − 151 =

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