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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 187 · 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. 1.410 + 136 =
  2. 2.851 − 606 =
  3. 3.206 + 367 =
  4. 4.561 − 417 =
  5. 5.679 − 302 =
  6. 6.861 − 563 =
  7. 7.888 − 357 =
  8. 8.783 + 181 =
  9. 9.301 + 201 =
  10. 10.148 + 486 =
  11. 11.636 + 621 =
  12. 12.490 + 473 =
  13. 13.532 − 382 =
  14. 14.671 − 221 =
  15. 15.548 − 304 =
  16. 16.435 + 246 =
  17. 17.371 + 281 =
  18. 18.559 + 502 =
  19. 19.615 − 346 =
  20. 20.457 + 325 =
  21. 21.891 − 769 =
  22. 22.647 − 267 =
  23. 23.609 − 248 =
  24. 24.630 − 301 =
  25. 25.880 − 204 =
  26. 26.798 − 378 =
  27. 27.545 − 222 =
  28. 28.284 + 183 =
  29. 29.904 − 553 =
  30. 30.218 + 331 =
  31. 31.819 − 666 =
  32. 32.177 + 351 =
  33. 33.963 − 551 =
  34. 34.567 − 237 =
  35. 35.460 − 191 =
  36. 36.421 − 193 =
  37. 37.207 + 614 =
  38. 38.448 − 152 =
  39. 39.887 − 748 =
  40. 40.675 − 446 =

Answer key

  1. 546
  2. 245
  3. 573
  4. 144
  5. 377
  6. 298
  7. 531
  8. 964
  9. 502
  10. 634
  11. 1257
  12. 963
  13. 150
  14. 450
  15. 244
  16. 681
  17. 652
  18. 1061
  19. 269
  20. 782
  21. 122
  22. 380
  23. 361
  24. 329
  25. 676
  26. 420
  27. 323
  28. 467
  29. 351
  30. 549
  31. 153
  32. 528
  33. 412
  34. 330
  35. 269
  36. 228
  37. 821
  38. 296
  39. 139
  40. 229

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