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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 876 · 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. 1.783 + 268 =
  2. 2.213 + 268 =
  3. 3.335 + 654 =
  4. 4.633 + 619 =
  5. 5.315 + 431 =
  6. 6.617 − 379 =
  7. 7.492 − 346 =
  8. 8.426 − 178 =
  9. 9.669 − 311 =
  10. 10.450 + 601 =
  11. 11.567 + 214 =
  12. 12.783 + 276 =
  13. 13.208 + 681 =
  14. 14.895 − 434 =
  15. 15.393 + 361 =
  16. 16.784 + 235 =
  17. 17.732 − 546 =
  18. 18.504 − 181 =
  19. 19.608 + 389 =
  20. 20.802 − 333 =
  21. 21.173 + 384 =
  22. 22.929 − 719 =
  23. 23.568 − 152 =
  24. 24.935 − 454 =
  25. 25.509 − 155 =
  26. 26.485 − 172 =
  27. 27.723 + 391 =
  28. 28.181 + 646 =
  29. 29.180 + 619 =
  30. 30.564 − 165 =
  31. 31.533 − 257 =
  32. 32.321 + 542 =
  33. 33.199 + 469 =
  34. 34.500 − 263 =
  35. 35.441 + 175 =
  36. 36.568 − 354 =
  37. 37.782 + 473 =
  38. 38.216 + 318 =
  39. 39.593 + 361 =
  40. 40.185 + 118 =

Answer key

  1. 1051
  2. 481
  3. 989
  4. 1252
  5. 746
  6. 238
  7. 146
  8. 248
  9. 358
  10. 1051
  11. 781
  12. 1059
  13. 889
  14. 461
  15. 754
  16. 1019
  17. 186
  18. 323
  19. 997
  20. 469
  21. 557
  22. 210
  23. 416
  24. 481
  25. 354
  26. 313
  27. 1114
  28. 827
  29. 799
  30. 399
  31. 276
  32. 863
  33. 668
  34. 237
  35. 616
  36. 214
  37. 1255
  38. 534
  39. 954
  40. 303

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