3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 368 · 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. 1.737 − 172 =
2. 2.809 − 685 =
3. 3.213 + 191 =
4. 4.718 − 281 =
5. 5.764 + 228 =
6. 6.860 − 702 =
7. 7.570 + 258 =
8. 8.939 − 389 =
9. 9.548 + 519 =
10. 10.155 + 239 =
11. 11.658 + 117 =
12. 12.537 − 144 =
13. 13.665 + 388 =
14. 14.267 + 135 =
15. 15.832 − 591 =
16. 16.953 − 634 =
17. 17.769 + 535 =
18. 18.918 − 296 =
19. 19.459 − 112 =
20. 20.691 − 189 =
21. 21.288 + 553 =
22. 22.960 − 844 =
23. 23.352 + 152 =
24. 24.681 + 203 =
25. 25.953 − 603 =
26. 26.553 + 596 =
27. 27.933 − 472 =
28. 28.822 − 553 =
29. 29.428 − 315 =
30. 30.159 + 429 =
31. 31.271 + 212 =
32. 32.444 + 375 =
33. 33.902 − 171 =
34. 34.872 − 303 =
35. 35.710 − 425 =
36. 36.920 − 153 =
37. 37.141 + 411 =
38. 38.633 − 463 =
39. 39.133 + 395 =
40. 40.601 − 129 =

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