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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 962 · 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. 1.516 + 246 =
  2. 2.389 + 255 =
  3. 3.561 − 276 =
  4. 4.835 − 305 =
  5. 5.252 + 402 =
  6. 6.196 + 525 =
  7. 7.641 + 559 =
  8. 8.460 − 304 =
  9. 9.344 + 225 =
  10. 10.741 − 331 =
  11. 11.576 + 141 =
  12. 12.586 − 182 =
  13. 13.526 + 271 =
  14. 14.198 + 681 =
  15. 15.625 − 376 =
  16. 16.616 − 315 =
  17. 17.327 + 471 =
  18. 18.742 − 375 =
  19. 19.664 + 257 =
  20. 20.362 + 521 =
  21. 21.855 − 381 =
  22. 22.375 + 575 =
  23. 23.453 + 203 =
  24. 24.561 − 253 =
  25. 25.604 − 144 =
  26. 26.396 + 227 =
  27. 27.960 − 712 =
  28. 28.745 + 298 =
  29. 29.920 − 635 =
  30. 30.881 − 526 =
  31. 31.522 − 289 =
  32. 32.636 + 411 =
  33. 33.957 − 689 =
  34. 34.703 + 637 =
  35. 35.576 − 351 =
  36. 36.412 − 157 =
  37. 37.260 + 531 =
  38. 38.786 + 343 =
  39. 39.763 + 272 =
  40. 40.399 + 515 =

Answer key

  1. 762
  2. 644
  3. 285
  4. 530
  5. 654
  6. 721
  7. 1200
  8. 156
  9. 569
  10. 410
  11. 717
  12. 404
  13. 797
  14. 879
  15. 249
  16. 301
  17. 798
  18. 367
  19. 921
  20. 883
  21. 474
  22. 950
  23. 656
  24. 308
  25. 460
  26. 623
  27. 248
  28. 1043
  29. 285
  30. 355
  31. 233
  32. 1047
  33. 268
  34. 1340
  35. 225
  36. 255
  37. 791
  38. 1129
  39. 1035
  40. 914

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