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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 51 · 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. 1.336 + 186 =
  2. 2.648 − 199 =
  3. 3.646 − 202 =
  4. 4.742 − 121 =
  5. 5.359 + 604 =
  6. 6.635 + 307 =
  7. 7.671 + 228 =
  8. 8.591 − 473 =
  9. 9.618 − 474 =
  10. 10.218 + 341 =
  11. 11.538 − 215 =
  12. 12.823 − 564 =
  13. 13.760 + 643 =
  14. 14.598 + 356 =
  15. 15.362 + 465 =
  16. 16.518 − 162 =
  17. 17.529 + 188 =
  18. 18.244 + 227 =
  19. 19.765 + 281 =
  20. 20.190 + 391 =
  21. 21.348 + 579 =
  22. 22.230 + 672 =
  23. 23.761 + 226 =
  24. 24.516 + 654 =
  25. 25.513 + 466 =
  26. 26.256 + 228 =
  27. 27.475 + 477 =
  28. 28.212 + 116 =
  29. 29.344 + 116 =
  30. 30.820 − 611 =
  31. 31.344 + 236 =
  32. 32.136 + 572 =
  33. 33.499 − 277 =
  34. 34.772 + 227 =
  35. 35.473 + 217 =
  36. 36.475 − 225 =
  37. 37.774 − 614 =
  38. 38.537 + 361 =
  39. 39.643 + 174 =
  40. 40.709 + 454 =

Answer key

  1. 522
  2. 449
  3. 444
  4. 621
  5. 963
  6. 942
  7. 899
  8. 118
  9. 144
  10. 559
  11. 323
  12. 259
  13. 1403
  14. 954
  15. 827
  16. 356
  17. 717
  18. 471
  19. 1046
  20. 581
  21. 927
  22. 902
  23. 987
  24. 1170
  25. 979
  26. 484
  27. 952
  28. 328
  29. 460
  30. 209
  31. 580
  32. 708
  33. 222
  34. 999
  35. 690
  36. 250
  37. 160
  38. 898
  39. 817
  40. 1163

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