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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 439 · 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. 1.541 − 171 =
  2. 2.598 + 156 =
  3. 3.735 + 445 =
  4. 4.283 + 537 =
  5. 5.928 − 306 =
  6. 6.718 + 164 =
  7. 7.274 + 328 =
  8. 8.962 − 624 =
  9. 9.430 − 254 =
  10. 10.631 + 407 =
  11. 11.530 − 192 =
  12. 12.478 − 369 =
  13. 13.768 + 574 =
  14. 14.810 − 221 =
  15. 15.764 − 186 =
  16. 16.558 − 392 =
  17. 17.215 + 354 =
  18. 18.446 + 244 =
  19. 19.623 + 207 =
  20. 20.424 − 282 =
  21. 21.780 − 544 =
  22. 22.753 − 626 =
  23. 23.743 + 477 =
  24. 24.787 + 454 =
  25. 25.704 + 139 =
  26. 26.783 + 484 =
  27. 27.245 + 488 =
  28. 28.593 − 468 =
  29. 29.556 + 593 =
  30. 30.551 − 187 =
  31. 31.594 − 202 =
  32. 32.265 + 521 =
  33. 33.183 + 192 =
  34. 34.752 − 642 =
  35. 35.890 − 724 =
  36. 36.377 + 616 =
  37. 37.598 + 666 =
  38. 38.417 − 242 =
  39. 39.736 + 679 =
  40. 40.233 + 272 =

Answer key

  1. 370
  2. 754
  3. 1180
  4. 820
  5. 622
  6. 882
  7. 602
  8. 338
  9. 176
  10. 1038
  11. 338
  12. 109
  13. 1342
  14. 589
  15. 578
  16. 166
  17. 569
  18. 690
  19. 830
  20. 142
  21. 236
  22. 127
  23. 1220
  24. 1241
  25. 843
  26. 1267
  27. 733
  28. 125
  29. 1149
  30. 364
  31. 392
  32. 786
  33. 375
  34. 110
  35. 166
  36. 993
  37. 1264
  38. 175
  39. 1415
  40. 505

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