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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 178 · 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. 1.726 − 221 =
  2. 2.723 + 394 =
  3. 3.770 + 419 =
  4. 4.528 − 381 =
  5. 5.776 − 137 =
  6. 6.160 + 224 =
  7. 7.323 + 128 =
  8. 8.447 − 249 =
  9. 9.798 − 406 =
  10. 10.515 − 412 =
  11. 11.980 − 467 =
  12. 12.294 + 195 =
  13. 13.966 − 858 =
  14. 14.691 + 652 =
  15. 15.330 + 534 =
  16. 16.215 + 199 =
  17. 17.550 − 414 =
  18. 18.545 − 371 =
  19. 19.895 − 181 =
  20. 20.621 + 657 =
  21. 21.510 − 121 =
  22. 22.965 − 606 =
  23. 23.951 − 425 =
  24. 24.460 − 115 =
  25. 25.138 + 172 =
  26. 26.499 + 254 =
  27. 27.138 + 337 =
  28. 28.902 − 189 =
  29. 29.769 − 511 =
  30. 30.652 + 686 =
  31. 31.680 + 329 =
  32. 32.932 − 746 =
  33. 33.177 + 635 =
  34. 34.678 + 674 =
  35. 35.677 − 359 =
  36. 36.883 − 593 =
  37. 37.518 + 296 =
  38. 38.619 − 435 =
  39. 39.242 + 483 =
  40. 40.611 + 544 =

Answer key

  1. 505
  2. 1117
  3. 1189
  4. 147
  5. 639
  6. 384
  7. 451
  8. 198
  9. 392
  10. 103
  11. 513
  12. 489
  13. 108
  14. 1343
  15. 864
  16. 414
  17. 136
  18. 174
  19. 714
  20. 1278
  21. 389
  22. 359
  23. 526
  24. 345
  25. 310
  26. 753
  27. 475
  28. 713
  29. 258
  30. 1338
  31. 1009
  32. 186
  33. 812
  34. 1352
  35. 318
  36. 290
  37. 814
  38. 184
  39. 725
  40. 1155

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