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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 741 · 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. 1.237 + 331 =
  2. 2.943 − 399 =
  3. 3.813 − 631 =
  4. 4.800 − 523 =
  5. 5.902 − 341 =
  6. 6.453 − 203 =
  7. 7.470 − 152 =
  8. 8.154 + 689 =
  9. 9.776 + 335 =
  10. 10.765 + 138 =
  11. 11.322 + 136 =
  12. 12.704 + 149 =
  13. 13.552 − 141 =
  14. 14.594 + 143 =
  15. 15.662 − 395 =
  16. 16.584 − 209 =
  17. 17.605 + 192 =
  18. 18.538 − 125 =
  19. 19.663 + 335 =
  20. 20.245 + 562 =
  21. 21.815 − 586 =
  22. 22.344 + 657 =
  23. 23.249 + 217 =
  24. 24.526 − 214 =
  25. 25.781 + 496 =
  26. 26.518 − 261 =
  27. 27.655 − 263 =
  28. 28.361 + 233 =
  29. 29.694 − 459 =
  30. 30.557 + 114 =
  31. 31.786 + 597 =
  32. 32.526 − 182 =
  33. 33.314 + 633 =
  34. 34.649 + 471 =
  35. 35.489 − 139 =
  36. 36.518 + 674 =
  37. 37.672 + 385 =
  38. 38.637 − 396 =
  39. 39.510 − 406 =
  40. 40.825 − 525 =

Answer key

  1. 568
  2. 544
  3. 182
  4. 277
  5. 561
  6. 250
  7. 318
  8. 843
  9. 1111
  10. 903
  11. 458
  12. 853
  13. 411
  14. 737
  15. 267
  16. 375
  17. 797
  18. 413
  19. 998
  20. 807
  21. 229
  22. 1001
  23. 466
  24. 312
  25. 1277
  26. 257
  27. 392
  28. 594
  29. 235
  30. 671
  31. 1383
  32. 344
  33. 947
  34. 1120
  35. 350
  36. 1192
  37. 1057
  38. 241
  39. 104
  40. 300

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