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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 469 · 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. 1.540 − 217 =
  2. 2.581 − 172 =
  3. 3.190 + 333 =
  4. 4.756 − 622 =
  5. 5.708 − 418 =
  6. 6.785 + 541 =
  7. 7.151 + 364 =
  8. 8.776 + 417 =
  9. 9.917 − 274 =
  10. 10.720 − 184 =
  11. 11.385 + 284 =
  12. 12.472 − 151 =
  13. 13.973 − 199 =
  14. 14.200 + 382 =
  15. 15.356 + 293 =
  16. 16.681 − 129 =
  17. 17.302 + 257 =
  18. 18.599 − 443 =
  19. 19.753 − 311 =
  20. 20.615 + 214 =
  21. 21.674 + 458 =
  22. 22.718 − 414 =
  23. 23.496 + 604 =
  24. 24.881 − 355 =
  25. 25.706 + 621 =
  26. 26.287 + 309 =
  27. 27.769 − 183 =
  28. 28.274 + 461 =
  29. 29.943 − 671 =
  30. 30.826 − 707 =
  31. 31.278 + 536 =
  32. 32.583 + 402 =
  33. 33.584 + 306 =
  34. 34.269 + 234 =
  35. 35.734 − 329 =
  36. 36.698 − 336 =
  37. 37.675 + 349 =
  38. 38.745 + 217 =
  39. 39.191 + 304 =
  40. 40.462 − 132 =

Answer key

  1. 323
  2. 409
  3. 523
  4. 134
  5. 290
  6. 1326
  7. 515
  8. 1193
  9. 643
  10. 536
  11. 669
  12. 321
  13. 774
  14. 582
  15. 649
  16. 552
  17. 559
  18. 156
  19. 442
  20. 829
  21. 1132
  22. 304
  23. 1100
  24. 526
  25. 1327
  26. 596
  27. 586
  28. 735
  29. 272
  30. 119
  31. 814
  32. 985
  33. 890
  34. 503
  35. 405
  36. 362
  37. 1024
  38. 962
  39. 495
  40. 330

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