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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 562 · 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. 1.942 − 254 =
  2. 2.857 − 442 =
  3. 3.593 − 328 =
  4. 4.487 + 639 =
  5. 5.475 − 157 =
  6. 6.239 + 608 =
  7. 7.487 − 192 =
  8. 8.738 − 288 =
  9. 9.457 + 407 =
  10. 10.662 + 558 =
  11. 11.906 − 557 =
  12. 12.724 − 268 =
  13. 13.719 − 428 =
  14. 14.733 − 361 =
  15. 15.760 + 281 =
  16. 16.231 + 321 =
  17. 17.627 + 342 =
  18. 18.470 − 291 =
  19. 19.971 − 432 =
  20. 20.413 + 449 =
  21. 21.771 + 389 =
  22. 22.377 + 601 =
  23. 23.904 − 254 =
  24. 24.182 + 634 =
  25. 25.462 + 221 =
  26. 26.430 + 449 =
  27. 27.921 − 821 =
  28. 28.610 + 171 =
  29. 29.514 + 401 =
  30. 30.355 + 155 =
  31. 31.415 + 506 =
  32. 32.831 − 622 =
  33. 33.503 + 471 =
  34. 34.769 + 158 =
  35. 35.273 + 359 =
  36. 36.418 + 531 =
  37. 37.300 + 629 =
  38. 38.216 + 667 =
  39. 39.335 + 529 =
  40. 40.536 + 612 =

Answer key

  1. 688
  2. 415
  3. 265
  4. 1126
  5. 318
  6. 847
  7. 295
  8. 450
  9. 864
  10. 1220
  11. 349
  12. 456
  13. 291
  14. 372
  15. 1041
  16. 552
  17. 969
  18. 179
  19. 539
  20. 862
  21. 1160
  22. 978
  23. 650
  24. 816
  25. 683
  26. 879
  27. 100
  28. 781
  29. 915
  30. 510
  31. 921
  32. 209
  33. 974
  34. 927
  35. 632
  36. 949
  37. 929
  38. 883
  39. 864
  40. 1148

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