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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 40 · 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. 1.599 + 112 =
  2. 2.215 + 362 =
  3. 3.848 − 709 =
  4. 4.510 + 239 =
  5. 5.884 − 709 =
  6. 6.818 − 691 =
  7. 7.595 + 648 =
  8. 8.452 + 565 =
  9. 9.835 − 306 =
  10. 10.440 + 636 =
  11. 11.806 − 434 =
  12. 12.554 + 407 =
  13. 13.423 − 222 =
  14. 14.958 − 827 =
  15. 15.512 − 289 =
  16. 16.561 − 271 =
  17. 17.722 + 211 =
  18. 18.460 + 214 =
  19. 19.721 + 575 =
  20. 20.803 − 177 =
  21. 21.850 − 182 =
  22. 22.574 + 435 =
  23. 23.885 − 423 =
  24. 24.370 + 199 =
  25. 25.932 − 523 =
  26. 26.606 − 451 =
  27. 27.579 − 394 =
  28. 28.620 + 437 =
  29. 29.614 − 193 =
  30. 30.522 − 228 =
  31. 31.307 + 652 =
  32. 32.554 + 624 =
  33. 33.133 + 414 =
  34. 34.528 − 366 =
  35. 35.325 + 591 =
  36. 36.691 − 421 =
  37. 37.537 + 283 =
  38. 38.712 − 581 =
  39. 39.500 − 233 =
  40. 40.919 − 235 =

Answer key

  1. 711
  2. 577
  3. 139
  4. 749
  5. 175
  6. 127
  7. 1243
  8. 1017
  9. 529
  10. 1076
  11. 372
  12. 961
  13. 201
  14. 131
  15. 223
  16. 290
  17. 933
  18. 674
  19. 1296
  20. 626
  21. 668
  22. 1009
  23. 462
  24. 569
  25. 409
  26. 155
  27. 185
  28. 1057
  29. 421
  30. 294
  31. 959
  32. 1178
  33. 547
  34. 162
  35. 916
  36. 270
  37. 820
  38. 131
  39. 267
  40. 684

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