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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 788 · 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. 1.416 + 557 =
  2. 2.129 + 501 =
  3. 3.415 − 259 =
  4. 4.339 + 128 =
  5. 5.132 + 114 =
  6. 6.447 − 184 =
  7. 7.457 − 204 =
  8. 8.662 + 455 =
  9. 9.237 + 475 =
  10. 10.195 + 243 =
  11. 11.318 + 381 =
  12. 12.685 − 271 =
  13. 13.467 − 303 =
  14. 14.476 − 239 =
  15. 15.692 − 402 =
  16. 16.350 + 361 =
  17. 17.665 − 462 =
  18. 18.438 − 116 =
  19. 19.631 + 654 =
  20. 20.313 + 342 =
  21. 21.926 − 663 =
  22. 22.490 − 235 =
  23. 23.201 + 146 =
  24. 24.290 + 302 =
  25. 25.540 − 287 =
  26. 26.751 + 511 =
  27. 27.495 − 376 =
  28. 28.723 + 513 =
  29. 29.651 − 221 =
  30. 30.369 + 645 =
  31. 31.704 + 369 =
  32. 32.455 + 212 =
  33. 33.939 − 179 =
  34. 34.582 + 307 =
  35. 35.265 + 622 =
  36. 36.768 + 182 =
  37. 37.785 − 381 =
  38. 38.474 + 601 =
  39. 39.414 + 249 =
  40. 40.388 + 633 =

Answer key

  1. 973
  2. 630
  3. 156
  4. 467
  5. 246
  6. 263
  7. 253
  8. 1117
  9. 712
  10. 438
  11. 699
  12. 414
  13. 164
  14. 237
  15. 290
  16. 711
  17. 203
  18. 322
  19. 1285
  20. 655
  21. 263
  22. 255
  23. 347
  24. 592
  25. 253
  26. 1262
  27. 119
  28. 1236
  29. 430
  30. 1014
  31. 1073
  32. 667
  33. 760
  34. 889
  35. 887
  36. 950
  37. 404
  38. 1075
  39. 663
  40. 1021

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