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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 416 · 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. 1.452 + 241 =
  2. 2.482 + 282 =
  3. 3.714 + 635 =
  4. 4.506 + 291 =
  5. 5.986 − 452 =
  6. 6.627 + 639 =
  7. 7.391 + 178 =
  8. 8.711 − 485 =
  9. 9.250 + 296 =
  10. 10.310 + 681 =
  11. 11.716 − 566 =
  12. 12.382 + 513 =
  13. 13.761 − 634 =
  14. 14.964 − 821 =
  15. 15.304 + 519 =
  16. 16.735 + 546 =
  17. 17.454 − 168 =
  18. 18.413 − 297 =
  19. 19.495 + 383 =
  20. 20.536 + 232 =
  21. 21.835 − 394 =
  22. 22.193 + 197 =
  23. 23.540 + 439 =
  24. 24.572 + 232 =
  25. 25.487 − 314 =
  26. 26.436 − 296 =
  27. 27.491 + 248 =
  28. 28.752 + 607 =
  29. 29.470 − 351 =
  30. 30.449 + 291 =
  31. 31.442 + 221 =
  32. 32.506 − 327 =
  33. 33.394 + 436 =
  34. 34.743 − 464 =
  35. 35.938 − 469 =
  36. 36.664 − 259 =
  37. 37.633 − 138 =
  38. 38.235 + 231 =
  39. 39.631 − 349 =
  40. 40.615 + 255 =

Answer key

  1. 693
  2. 764
  3. 1349
  4. 797
  5. 534
  6. 1266
  7. 569
  8. 226
  9. 546
  10. 991
  11. 150
  12. 895
  13. 127
  14. 143
  15. 823
  16. 1281
  17. 286
  18. 116
  19. 878
  20. 768
  21. 441
  22. 390
  23. 979
  24. 804
  25. 173
  26. 140
  27. 739
  28. 1359
  29. 119
  30. 740
  31. 663
  32. 179
  33. 830
  34. 279
  35. 469
  36. 405
  37. 495
  38. 466
  39. 282
  40. 870

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