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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 234 · 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. 1.509 − 294 =
  2. 2.178 + 418 =
  3. 3.701 + 546 =
  4. 4.510 − 382 =
  5. 5.454 + 414 =
  6. 6.835 − 411 =
  7. 7.505 + 661 =
  8. 8.669 + 137 =
  9. 9.565 + 456 =
  10. 10.571 + 295 =
  11. 11.935 − 754 =
  12. 12.630 + 511 =
  13. 13.570 − 162 =
  14. 14.858 − 551 =
  15. 15.488 − 171 =
  16. 16.245 + 652 =
  17. 17.346 + 663 =
  18. 18.438 − 307 =
  19. 19.132 + 468 =
  20. 20.916 − 611 =
  21. 21.877 − 578 =
  22. 22.699 − 321 =
  23. 23.968 − 354 =
  24. 24.562 − 222 =
  25. 25.782 + 597 =
  26. 26.682 − 182 =
  27. 27.922 − 554 =
  28. 28.328 + 619 =
  29. 29.786 + 166 =
  30. 30.198 + 451 =
  31. 31.173 + 519 =
  32. 32.411 + 577 =
  33. 33.654 − 184 =
  34. 34.770 − 268 =
  35. 35.772 − 281 =
  36. 36.400 + 202 =
  37. 37.596 + 585 =
  38. 38.967 − 763 =
  39. 39.635 + 515 =
  40. 40.714 − 398 =

Answer key

  1. 215
  2. 596
  3. 1247
  4. 128
  5. 868
  6. 424
  7. 1166
  8. 806
  9. 1021
  10. 866
  11. 181
  12. 1141
  13. 408
  14. 307
  15. 317
  16. 897
  17. 1009
  18. 131
  19. 600
  20. 305
  21. 299
  22. 378
  23. 614
  24. 340
  25. 1379
  26. 500
  27. 368
  28. 947
  29. 952
  30. 649
  31. 692
  32. 988
  33. 470
  34. 502
  35. 491
  36. 602
  37. 1181
  38. 204
  39. 1150
  40. 316

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