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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 88 · 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. 1.246 + 559 =
  2. 2.358 + 293 =
  3. 3.887 − 442 =
  4. 4.763 + 343 =
  5. 5.726 − 327 =
  6. 6.879 − 401 =
  7. 7.601 + 346 =
  8. 8.543 − 427 =
  9. 9.155 + 246 =
  10. 10.496 + 623 =
  11. 11.692 + 428 =
  12. 12.717 − 184 =
  13. 13.821 − 265 =
  14. 14.521 + 333 =
  15. 15.432 − 191 =
  16. 16.775 − 358 =
  17. 17.690 − 227 =
  18. 18.826 − 561 =
  19. 19.166 + 245 =
  20. 20.378 + 343 =
  21. 21.197 + 298 =
  22. 22.434 + 227 =
  23. 23.707 + 297 =
  24. 24.612 − 248 =
  25. 25.262 + 121 =
  26. 26.709 − 368 =
  27. 27.685 + 493 =
  28. 28.856 − 127 =
  29. 29.126 + 127 =
  30. 30.488 + 371 =
  31. 31.123 + 154 =
  32. 32.789 − 385 =
  33. 33.472 − 312 =
  34. 34.902 − 159 =
  35. 35.575 + 482 =
  36. 36.479 − 379 =
  37. 37.268 + 249 =
  38. 38.971 − 221 =
  39. 39.812 − 183 =
  40. 40.158 + 497 =

Answer key

  1. 805
  2. 651
  3. 445
  4. 1106
  5. 399
  6. 478
  7. 947
  8. 116
  9. 401
  10. 1119
  11. 1120
  12. 533
  13. 556
  14. 854
  15. 241
  16. 417
  17. 463
  18. 265
  19. 411
  20. 721
  21. 495
  22. 661
  23. 1004
  24. 364
  25. 383
  26. 341
  27. 1178
  28. 729
  29. 253
  30. 859
  31. 277
  32. 404
  33. 160
  34. 743
  35. 1057
  36. 100
  37. 517
  38. 750
  39. 629
  40. 655

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