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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 763 · 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. 1.295 + 182 =
  2. 2.702 + 188 =
  3. 3.452 + 124 =
  4. 4.932 − 664 =
  5. 5.536 − 192 =
  6. 6.457 + 391 =
  7. 7.156 + 288 =
  8. 8.247 + 476 =
  9. 9.421 + 154 =
  10. 10.445 + 297 =
  11. 11.911 − 167 =
  12. 12.629 + 343 =
  13. 13.430 + 131 =
  14. 14.534 + 182 =
  15. 15.877 − 294 =
  16. 16.254 + 155 =
  17. 17.542 − 118 =
  18. 18.197 + 124 =
  19. 19.811 − 485 =
  20. 20.825 − 523 =
  21. 21.464 − 131 =
  22. 22.460 − 148 =
  23. 23.701 + 645 =
  24. 24.708 + 299 =
  25. 25.710 − 599 =
  26. 26.589 + 293 =
  27. 27.625 − 455 =
  28. 28.391 + 403 =
  29. 29.669 + 436 =
  30. 30.583 − 295 =
  31. 31.571 − 156 =
  32. 32.200 + 279 =
  33. 33.255 + 137 =
  34. 34.372 + 399 =
  35. 35.939 − 839 =
  36. 36.526 − 336 =
  37. 37.739 + 229 =
  38. 38.864 − 491 =
  39. 39.663 + 656 =
  40. 40.639 + 565 =

Answer key

  1. 477
  2. 890
  3. 576
  4. 268
  5. 344
  6. 848
  7. 444
  8. 723
  9. 575
  10. 742
  11. 744
  12. 972
  13. 561
  14. 716
  15. 583
  16. 409
  17. 424
  18. 321
  19. 326
  20. 302
  21. 333
  22. 312
  23. 1346
  24. 1007
  25. 111
  26. 882
  27. 170
  28. 794
  29. 1105
  30. 288
  31. 415
  32. 479
  33. 392
  34. 771
  35. 100
  36. 190
  37. 968
  38. 373
  39. 1319
  40. 1204

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