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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 693 · 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. 1.679 + 564 =
  2. 2.141 + 158 =
  3. 3.521 + 347 =
  4. 4.153 + 371 =
  5. 5.307 + 315 =
  6. 6.649 − 201 =
  7. 7.840 − 439 =
  8. 8.466 − 208 =
  9. 9.550 + 486 =
  10. 10.926 − 547 =
  11. 11.711 + 214 =
  12. 12.610 + 642 =
  13. 13.251 + 384 =
  14. 14.140 + 619 =
  15. 15.688 − 207 =
  16. 16.512 − 152 =
  17. 17.792 − 418 =
  18. 18.365 + 395 =
  19. 19.201 + 166 =
  20. 20.628 − 154 =
  21. 21.863 − 484 =
  22. 22.546 − 351 =
  23. 23.417 − 121 =
  24. 24.635 − 361 =
  25. 25.389 + 671 =
  26. 26.763 + 282 =
  27. 27.558 − 154 =
  28. 28.575 − 274 =
  29. 29.936 − 805 =
  30. 30.619 − 258 =
  31. 31.769 + 523 =
  32. 32.454 + 644 =
  33. 33.557 − 387 =
  34. 34.200 + 275 =
  35. 35.635 + 209 =
  36. 36.602 + 257 =
  37. 37.835 − 547 =
  38. 38.152 + 548 =
  39. 39.779 − 164 =
  40. 40.696 + 648 =

Answer key

  1. 1243
  2. 299
  3. 868
  4. 524
  5. 622
  6. 448
  7. 401
  8. 258
  9. 1036
  10. 379
  11. 925
  12. 1252
  13. 635
  14. 759
  15. 481
  16. 360
  17. 374
  18. 760
  19. 367
  20. 474
  21. 379
  22. 195
  23. 296
  24. 274
  25. 1060
  26. 1045
  27. 404
  28. 301
  29. 131
  30. 361
  31. 1292
  32. 1098
  33. 170
  34. 475
  35. 844
  36. 859
  37. 288
  38. 700
  39. 615
  40. 1344

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