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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 712 · 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. 1.719 − 128 =
  2. 2.767 + 295 =
  3. 3.716 + 501 =
  4. 4.256 + 207 =
  5. 5.480 + 121 =
  6. 6.676 + 473 =
  7. 7.762 − 385 =
  8. 8.745 + 658 =
  9. 9.348 + 392 =
  10. 10.534 − 285 =
  11. 11.251 + 538 =
  12. 12.467 − 351 =
  13. 13.814 − 218 =
  14. 14.405 + 613 =
  15. 15.449 − 291 =
  16. 16.890 − 531 =
  17. 17.783 + 153 =
  18. 18.744 + 514 =
  19. 19.934 − 786 =
  20. 20.808 − 343 =
  21. 21.655 − 343 =
  22. 22.505 − 384 =
  23. 23.835 − 615 =
  24. 24.130 + 168 =
  25. 25.406 + 685 =
  26. 26.794 − 331 =
  27. 27.815 − 702 =
  28. 28.820 − 331 =
  29. 29.459 − 297 =
  30. 30.350 + 358 =
  31. 31.466 + 187 =
  32. 32.771 − 373 =
  33. 33.775 − 451 =
  34. 34.150 + 136 =
  35. 35.253 + 558 =
  36. 36.932 − 586 =
  37. 37.451 + 154 =
  38. 38.697 + 271 =
  39. 39.161 + 112 =
  40. 40.298 + 324 =

Answer key

  1. 591
  2. 1062
  3. 1217
  4. 463
  5. 601
  6. 1149
  7. 377
  8. 1403
  9. 740
  10. 249
  11. 789
  12. 116
  13. 596
  14. 1018
  15. 158
  16. 359
  17. 936
  18. 1258
  19. 148
  20. 465
  21. 312
  22. 121
  23. 220
  24. 298
  25. 1091
  26. 463
  27. 113
  28. 489
  29. 162
  30. 708
  31. 653
  32. 398
  33. 324
  34. 286
  35. 811
  36. 346
  37. 605
  38. 968
  39. 273
  40. 622

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