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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 806 · 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. 1.466 − 328 =
  2. 2.587 − 304 =
  3. 3.397 + 644 =
  4. 4.649 + 537 =
  5. 5.292 + 318 =
  6. 6.434 − 274 =
  7. 7.940 − 471 =
  8. 8.525 + 641 =
  9. 9.132 + 347 =
  10. 10.902 − 392 =
  11. 11.693 − 445 =
  12. 12.840 − 207 =
  13. 13.562 + 168 =
  14. 14.517 − 159 =
  15. 15.234 + 537 =
  16. 16.649 − 193 =
  17. 17.657 − 158 =
  18. 18.609 − 128 =
  19. 19.895 − 612 =
  20. 20.697 − 165 =
  21. 21.428 − 131 =
  22. 22.580 − 434 =
  23. 23.689 − 197 =
  24. 24.962 − 141 =
  25. 25.688 + 304 =
  26. 26.180 + 156 =
  27. 27.743 − 158 =
  28. 28.264 + 635 =
  29. 29.722 + 502 =
  30. 30.775 − 373 =
  31. 31.922 − 146 =
  32. 32.715 + 338 =
  33. 33.507 − 199 =
  34. 34.198 + 201 =
  35. 35.255 + 499 =
  36. 36.784 + 236 =
  37. 37.681 − 184 =
  38. 38.584 − 183 =
  39. 39.664 + 488 =
  40. 40.473 + 138 =

Answer key

  1. 138
  2. 283
  3. 1041
  4. 1186
  5. 610
  6. 160
  7. 469
  8. 1166
  9. 479
  10. 510
  11. 248
  12. 633
  13. 730
  14. 358
  15. 771
  16. 456
  17. 499
  18. 481
  19. 283
  20. 532
  21. 297
  22. 146
  23. 492
  24. 821
  25. 992
  26. 336
  27. 585
  28. 899
  29. 1224
  30. 402
  31. 776
  32. 1053
  33. 308
  34. 399
  35. 754
  36. 1020
  37. 497
  38. 401
  39. 1152
  40. 611

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