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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 776 · 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. 1.677 − 201 =
  2. 2.821 − 624 =
  3. 3.262 + 468 =
  4. 4.539 − 271 =
  5. 5.208 + 584 =
  6. 6.444 − 115 =
  7. 7.578 − 207 =
  8. 8.625 − 402 =
  9. 9.525 − 265 =
  10. 10.596 − 311 =
  11. 11.776 + 385 =
  12. 12.391 + 689 =
  13. 13.487 + 296 =
  14. 14.300 + 527 =
  15. 15.313 + 114 =
  16. 16.607 + 142 =
  17. 17.427 + 501 =
  18. 18.406 + 669 =
  19. 19.730 − 348 =
  20. 20.822 − 485 =
  21. 21.240 + 288 =
  22. 22.754 + 252 =
  23. 23.412 − 168 =
  24. 24.584 + 576 =
  25. 25.923 − 403 =
  26. 26.394 + 516 =
  27. 27.599 + 392 =
  28. 28.536 + 581 =
  29. 29.631 − 417 =
  30. 30.560 + 257 =
  31. 31.553 + 509 =
  32. 32.323 + 667 =
  33. 33.618 − 136 =
  34. 34.263 + 341 =
  35. 35.445 − 171 =
  36. 36.444 − 233 =
  37. 37.477 + 305 =
  38. 38.301 + 333 =
  39. 39.582 + 121 =
  40. 40.373 + 339 =

Answer key

  1. 476
  2. 197
  3. 730
  4. 268
  5. 792
  6. 329
  7. 371
  8. 223
  9. 260
  10. 285
  11. 1161
  12. 1080
  13. 783
  14. 827
  15. 427
  16. 749
  17. 928
  18. 1075
  19. 382
  20. 337
  21. 528
  22. 1006
  23. 244
  24. 1160
  25. 520
  26. 910
  27. 991
  28. 1117
  29. 214
  30. 817
  31. 1062
  32. 990
  33. 482
  34. 604
  35. 274
  36. 211
  37. 782
  38. 634
  39. 703
  40. 712

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