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3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 233 · 40 questions
TalentJR

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.

NameDateTime takenScore ___ / 40
  1. 1.525 − 249 =
  2. 2.550 − 447 =
  3. 3.154 + 363 =
  4. 4.477 + 241 =
  5. 5.965 − 156 =
  6. 6.731 + 247 =
  7. 7.536 + 121 =
  8. 8.183 + 334 =
  9. 9.274 + 541 =
  10. 10.384 + 434 =
  11. 11.514 − 166 =
  12. 12.148 + 627 =
  13. 13.676 + 203 =
  14. 14.646 − 124 =
  15. 15.758 + 475 =
  16. 16.247 + 302 =
  17. 17.498 + 657 =
  18. 18.805 − 429 =
  19. 19.160 + 539 =
  20. 20.643 + 611 =
  21. 21.469 + 616 =
  22. 22.874 − 695 =
  23. 23.711 + 433 =
  24. 24.534 − 208 =
  25. 25.830 − 517 =
  26. 26.212 + 396 =
  27. 27.597 − 212 =
  28. 28.508 − 181 =
  29. 29.478 − 253 =
  30. 30.308 + 346 =
  31. 31.837 − 671 =
  32. 32.177 + 319 =
  33. 33.471 − 149 =
  34. 34.864 − 642 =
  35. 35.398 + 351 =
  36. 36.515 − 168 =
  37. 37.531 + 532 =
  38. 38.767 − 155 =
  39. 39.970 − 198 =
  40. 40.338 + 495 =

Answer key

  1. 276
  2. 103
  3. 517
  4. 718
  5. 809
  6. 978
  7. 657
  8. 517
  9. 815
  10. 818
  11. 348
  12. 775
  13. 879
  14. 522
  15. 1233
  16. 549
  17. 1155
  18. 376
  19. 699
  20. 1254
  21. 1085
  22. 179
  23. 1144
  24. 326
  25. 313
  26. 608
  27. 385
  28. 327
  29. 225
  30. 654
  31. 166
  32. 496
  33. 322
  34. 222
  35. 749
  36. 347
  37. 1063
  38. 612
  39. 772
  40. 833

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