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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 700 · 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. 1.350 + 201 =
  2. 2.425 + 491 =
  3. 3.588 − 253 =
  4. 4.299 + 437 =
  5. 5.343 + 668 =
  6. 6.570 + 639 =
  7. 7.201 + 588 =
  8. 8.400 + 236 =
  9. 9.712 − 206 =
  10. 10.832 − 391 =
  11. 11.956 − 404 =
  12. 12.492 − 333 =
  13. 13.671 − 489 =
  14. 14.512 + 267 =
  15. 15.723 − 291 =
  16. 16.299 + 431 =
  17. 17.881 − 342 =
  18. 18.984 − 207 =
  19. 19.756 − 242 =
  20. 20.547 − 184 =
  21. 21.331 + 149 =
  22. 22.680 + 143 =
  23. 23.263 + 646 =
  24. 24.696 + 201 =
  25. 25.859 − 235 =
  26. 26.169 + 209 =
  27. 27.965 − 535 =
  28. 28.605 − 129 =
  29. 29.172 + 517 =
  30. 30.707 + 171 =
  31. 31.518 + 401 =
  32. 32.463 − 179 =
  33. 33.740 + 353 =
  34. 34.655 + 676 =
  35. 35.383 + 299 =
  36. 36.199 + 446 =
  37. 37.644 − 506 =
  38. 38.688 − 518 =
  39. 39.578 − 381 =
  40. 40.355 + 123 =

Answer key

  1. 551
  2. 916
  3. 335
  4. 736
  5. 1011
  6. 1209
  7. 789
  8. 636
  9. 506
  10. 441
  11. 552
  12. 159
  13. 182
  14. 779
  15. 432
  16. 730
  17. 539
  18. 777
  19. 514
  20. 363
  21. 480
  22. 823
  23. 909
  24. 897
  25. 624
  26. 378
  27. 430
  28. 476
  29. 689
  30. 878
  31. 919
  32. 284
  33. 1093
  34. 1331
  35. 682
  36. 645
  37. 138
  38. 170
  39. 197
  40. 478

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