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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 262 · 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. 1.292 + 148 =
  2. 2.668 + 471 =
  3. 3.314 + 472 =
  4. 4.732 + 252 =
  5. 5.787 − 351 =
  6. 6.199 + 347 =
  7. 7.496 + 127 =
  8. 8.812 − 171 =
  9. 9.281 + 469 =
  10. 10.511 + 471 =
  11. 11.575 + 267 =
  12. 12.562 − 164 =
  13. 13.961 − 191 =
  14. 14.582 − 142 =
  15. 15.146 + 198 =
  16. 16.832 − 459 =
  17. 17.499 + 525 =
  18. 18.583 − 182 =
  19. 19.604 − 157 =
  20. 20.483 + 571 =
  21. 21.775 − 481 =
  22. 22.606 + 218 =
  23. 23.810 − 145 =
  24. 24.904 − 247 =
  25. 25.654 + 126 =
  26. 26.349 + 447 =
  27. 27.174 + 305 =
  28. 28.180 + 232 =
  29. 29.945 − 786 =
  30. 30.298 + 222 =
  31. 31.215 + 258 =
  32. 32.350 + 319 =
  33. 33.222 + 601 =
  34. 34.366 + 635 =
  35. 35.906 − 744 =
  36. 36.123 + 228 =
  37. 37.430 − 255 =
  38. 38.820 − 322 =
  39. 39.815 − 264 =
  40. 40.644 + 492 =

Answer key

  1. 440
  2. 1139
  3. 786
  4. 984
  5. 436
  6. 546
  7. 623
  8. 641
  9. 750
  10. 982
  11. 842
  12. 398
  13. 770
  14. 440
  15. 344
  16. 373
  17. 1024
  18. 401
  19. 447
  20. 1054
  21. 294
  22. 824
  23. 665
  24. 657
  25. 780
  26. 796
  27. 479
  28. 412
  29. 159
  30. 520
  31. 473
  32. 669
  33. 823
  34. 1001
  35. 162
  36. 351
  37. 175
  38. 498
  39. 551
  40. 1136

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