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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 459 · 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. 1.906 − 477 =
  2. 2.511 − 117 =
  3. 3.621 − 494 =
  4. 4.198 + 175 =
  5. 5.943 − 737 =
  6. 6.480 + 504 =
  7. 7.796 − 414 =
  8. 8.783 + 366 =
  9. 9.683 − 303 =
  10. 10.712 + 391 =
  11. 11.500 + 581 =
  12. 12.684 − 494 =
  13. 13.393 + 249 =
  14. 14.142 + 627 =
  15. 15.556 − 206 =
  16. 16.813 − 263 =
  17. 17.205 + 321 =
  18. 18.508 − 266 =
  19. 19.625 − 167 =
  20. 20.206 + 317 =
  21. 21.595 + 248 =
  22. 22.347 + 211 =
  23. 23.753 − 243 =
  24. 24.501 − 325 =
  25. 25.421 + 387 =
  26. 26.917 − 728 =
  27. 27.268 + 391 =
  28. 28.901 − 159 =
  29. 29.383 + 534 =
  30. 30.685 − 489 =
  31. 31.703 + 461 =
  32. 32.761 + 621 =
  33. 33.514 − 413 =
  34. 34.754 + 307 =
  35. 35.949 − 729 =
  36. 36.480 + 232 =
  37. 37.634 − 436 =
  38. 38.253 + 579 =
  39. 39.970 − 255 =
  40. 40.715 − 594 =

Answer key

  1. 429
  2. 394
  3. 127
  4. 373
  5. 206
  6. 984
  7. 382
  8. 1149
  9. 380
  10. 1103
  11. 1081
  12. 190
  13. 642
  14. 769
  15. 350
  16. 550
  17. 526
  18. 242
  19. 458
  20. 523
  21. 843
  22. 558
  23. 510
  24. 176
  25. 808
  26. 189
  27. 659
  28. 742
  29. 917
  30. 196
  31. 1164
  32. 1382
  33. 101
  34. 1061
  35. 220
  36. 712
  37. 198
  38. 832
  39. 715
  40. 121

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