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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 121 · 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. 1.936 − 733 =
  2. 2.636 + 371 =
  3. 3.572 + 127 =
  4. 4.363 + 234 =
  5. 5.526 + 631 =
  6. 6.700 + 216 =
  7. 7.291 + 372 =
  8. 8.891 − 595 =
  9. 9.951 − 469 =
  10. 10.707 − 211 =
  11. 11.421 + 374 =
  12. 12.514 + 254 =
  13. 13.546 + 116 =
  14. 14.543 − 271 =
  15. 15.763 + 174 =
  16. 16.469 + 591 =
  17. 17.718 + 479 =
  18. 18.622 − 355 =
  19. 19.397 + 274 =
  20. 20.624 + 164 =
  21. 21.688 + 179 =
  22. 22.761 − 329 =
  23. 23.422 − 212 =
  24. 24.699 − 301 =
  25. 25.129 + 507 =
  26. 26.729 + 292 =
  27. 27.214 + 157 =
  28. 28.225 + 191 =
  29. 29.422 + 122 =
  30. 30.831 − 551 =
  31. 31.205 + 176 =
  32. 32.502 + 281 =
  33. 33.563 − 221 =
  34. 34.433 − 316 =
  35. 35.276 + 656 =
  36. 36.310 + 523 =
  37. 37.363 + 112 =
  38. 38.502 − 137 =
  39. 39.260 + 679 =
  40. 40.529 − 417 =

Answer key

  1. 203
  2. 1007
  3. 699
  4. 597
  5. 1157
  6. 916
  7. 663
  8. 296
  9. 482
  10. 496
  11. 795
  12. 768
  13. 662
  14. 272
  15. 937
  16. 1060
  17. 1197
  18. 267
  19. 671
  20. 788
  21. 867
  22. 432
  23. 210
  24. 398
  25. 636
  26. 1021
  27. 371
  28. 416
  29. 544
  30. 280
  31. 381
  32. 783
  33. 342
  34. 117
  35. 932
  36. 833
  37. 475
  38. 365
  39. 939
  40. 112

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