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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 277 · 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. 1.486 − 215 =
  2. 2.147 + 267 =
  3. 3.628 + 634 =
  4. 4.484 − 121 =
  5. 5.199 + 184 =
  6. 6.733 + 462 =
  7. 7.423 − 133 =
  8. 8.910 − 249 =
  9. 9.532 − 419 =
  10. 10.292 + 511 =
  11. 11.325 + 488 =
  12. 12.680 + 458 =
  13. 13.194 + 211 =
  14. 14.789 + 398 =
  15. 15.559 − 452 =
  16. 16.717 + 603 =
  17. 17.432 + 252 =
  18. 18.627 + 665 =
  19. 19.232 + 506 =
  20. 20.350 + 312 =
  21. 21.451 − 338 =
  22. 22.190 + 524 =
  23. 23.657 − 532 =
  24. 24.962 − 311 =
  25. 25.754 + 631 =
  26. 26.660 − 159 =
  27. 27.268 + 273 =
  28. 28.537 + 444 =
  29. 29.583 + 375 =
  30. 30.412 − 308 =
  31. 31.562 − 113 =
  32. 32.366 + 538 =
  33. 33.803 − 182 =
  34. 34.858 − 171 =
  35. 35.732 + 557 =
  36. 36.728 − 416 =
  37. 37.689 + 542 =
  38. 38.627 + 251 =
  39. 39.473 + 316 =
  40. 40.562 − 323 =

Answer key

  1. 271
  2. 414
  3. 1262
  4. 363
  5. 383
  6. 1195
  7. 290
  8. 661
  9. 113
  10. 803
  11. 813
  12. 1138
  13. 405
  14. 1187
  15. 107
  16. 1320
  17. 684
  18. 1292
  19. 738
  20. 662
  21. 113
  22. 714
  23. 125
  24. 651
  25. 1385
  26. 501
  27. 541
  28. 981
  29. 958
  30. 104
  31. 449
  32. 904
  33. 621
  34. 687
  35. 1289
  36. 312
  37. 1231
  38. 878
  39. 789
  40. 239

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