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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 142 · 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. 1.700 + 493 =
  2. 2.663 − 232 =
  3. 3.959 − 458 =
  4. 4.626 − 469 =
  5. 5.573 + 433 =
  6. 6.165 + 226 =
  7. 7.733 − 142 =
  8. 8.261 + 321 =
  9. 9.384 + 389 =
  10. 10.417 − 255 =
  11. 11.683 − 271 =
  12. 12.525 − 391 =
  13. 13.734 + 542 =
  14. 14.143 + 306 =
  15. 15.367 + 568 =
  16. 16.170 + 484 =
  17. 17.493 − 331 =
  18. 18.231 + 496 =
  19. 19.269 + 271 =
  20. 20.502 + 403 =
  21. 21.454 − 203 =
  22. 22.712 − 122 =
  23. 23.784 − 151 =
  24. 24.491 + 221 =
  25. 25.457 + 253 =
  26. 26.575 − 284 =
  27. 27.889 − 586 =
  28. 28.658 + 649 =
  29. 29.722 − 242 =
  30. 30.543 − 121 =
  31. 31.224 + 127 =
  32. 32.392 + 224 =
  33. 33.566 − 377 =
  34. 34.631 − 467 =
  35. 35.239 + 131 =
  36. 36.548 + 261 =
  37. 37.883 − 665 =
  38. 38.696 − 435 =
  39. 39.663 + 446 =
  40. 40.733 − 276 =

Answer key

  1. 1193
  2. 431
  3. 501
  4. 157
  5. 1006
  6. 391
  7. 591
  8. 582
  9. 773
  10. 162
  11. 412
  12. 134
  13. 1276
  14. 449
  15. 935
  16. 654
  17. 162
  18. 727
  19. 540
  20. 905
  21. 251
  22. 590
  23. 633
  24. 712
  25. 710
  26. 291
  27. 303
  28. 1307
  29. 480
  30. 422
  31. 351
  32. 616
  33. 189
  34. 164
  35. 370
  36. 809
  37. 218
  38. 261
  39. 1109
  40. 457

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