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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 184 · 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. 1.828 − 278 =
  2. 2.134 + 215 =
  3. 3.635 + 379 =
  4. 4.572 − 232 =
  5. 5.379 + 594 =
  6. 6.409 + 515 =
  7. 7.634 − 286 =
  8. 8.509 + 152 =
  9. 9.931 − 759 =
  10. 10.635 − 136 =
  11. 11.540 − 122 =
  12. 12.133 + 397 =
  13. 13.734 + 476 =
  14. 14.588 − 425 =
  15. 15.878 − 696 =
  16. 16.222 + 143 =
  17. 17.619 − 271 =
  18. 18.220 + 495 =
  19. 19.628 + 491 =
  20. 20.597 + 631 =
  21. 21.544 − 182 =
  22. 22.596 + 677 =
  23. 23.636 − 158 =
  24. 24.709 − 368 =
  25. 25.506 + 138 =
  26. 26.508 − 149 =
  27. 27.736 − 441 =
  28. 28.932 − 331 =
  29. 29.837 − 158 =
  30. 30.717 − 443 =
  31. 31.612 − 166 =
  32. 32.631 − 495 =
  33. 33.595 + 116 =
  34. 34.398 + 616 =
  35. 35.535 − 324 =
  36. 36.500 + 592 =
  37. 37.542 − 381 =
  38. 38.192 + 161 =
  39. 39.591 − 296 =
  40. 40.655 + 631 =

Answer key

  1. 550
  2. 349
  3. 1014
  4. 340
  5. 973
  6. 924
  7. 348
  8. 661
  9. 172
  10. 499
  11. 418
  12. 530
  13. 1210
  14. 163
  15. 182
  16. 365
  17. 348
  18. 715
  19. 1119
  20. 1228
  21. 362
  22. 1273
  23. 478
  24. 341
  25. 644
  26. 359
  27. 295
  28. 601
  29. 679
  30. 274
  31. 446
  32. 136
  33. 711
  34. 1014
  35. 211
  36. 1092
  37. 161
  38. 353
  39. 295
  40. 1286

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