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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 917 · 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. 1.499 − 395 =
  2. 2.169 + 217 =
  3. 3.597 − 259 =
  4. 4.522 − 129 =
  5. 5.538 − 204 =
  6. 6.546 − 307 =
  7. 7.919 − 506 =
  8. 8.949 − 329 =
  9. 9.551 − 292 =
  10. 10.712 − 212 =
  11. 11.289 + 671 =
  12. 12.583 − 427 =
  13. 13.935 − 389 =
  14. 14.277 + 341 =
  15. 15.812 − 149 =
  16. 16.565 − 412 =
  17. 17.862 − 202 =
  18. 18.591 + 206 =
  19. 19.160 + 371 =
  20. 20.638 − 148 =
  21. 21.432 − 208 =
  22. 22.811 − 323 =
  23. 23.705 + 286 =
  24. 24.416 − 294 =
  25. 25.620 + 528 =
  26. 26.498 − 254 =
  27. 27.912 − 382 =
  28. 28.235 + 411 =
  29. 29.451 + 241 =
  30. 30.147 + 266 =
  31. 31.153 + 623 =
  32. 32.555 + 241 =
  33. 33.220 + 546 =
  34. 34.791 − 361 =
  35. 35.480 − 292 =
  36. 36.731 − 224 =
  37. 37.288 + 626 =
  38. 38.669 + 241 =
  39. 39.878 − 597 =
  40. 40.855 − 189 =

Answer key

  1. 104
  2. 386
  3. 338
  4. 393
  5. 334
  6. 239
  7. 413
  8. 620
  9. 259
  10. 500
  11. 960
  12. 156
  13. 546
  14. 618
  15. 663
  16. 153
  17. 660
  18. 797
  19. 531
  20. 490
  21. 224
  22. 488
  23. 991
  24. 122
  25. 1148
  26. 244
  27. 530
  28. 646
  29. 692
  30. 413
  31. 776
  32. 796
  33. 766
  34. 430
  35. 188
  36. 507
  37. 914
  38. 910
  39. 281
  40. 666

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