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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 351 · 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. 1.457 − 129 =
  2. 2.470 − 278 =
  3. 3.138 + 207 =
  4. 4.574 + 631 =
  5. 5.469 − 304 =
  6. 6.524 + 222 =
  7. 7.504 + 215 =
  8. 8.609 − 456 =
  9. 9.782 + 448 =
  10. 10.620 − 332 =
  11. 11.614 + 338 =
  12. 12.530 − 244 =
  13. 13.670 − 371 =
  14. 14.762 − 203 =
  15. 15.445 − 253 =
  16. 16.179 + 358 =
  17. 17.448 + 305 =
  18. 18.426 − 205 =
  19. 19.565 + 166 =
  20. 20.751 − 136 =
  21. 21.611 − 332 =
  22. 22.776 − 196 =
  23. 23.549 + 635 =
  24. 24.311 + 195 =
  25. 25.770 + 205 =
  26. 26.395 + 221 =
  27. 27.527 + 516 =
  28. 28.502 − 281 =
  29. 29.283 + 305 =
  30. 30.674 − 133 =
  31. 31.830 − 396 =
  32. 32.441 − 124 =
  33. 33.654 + 258 =
  34. 34.521 − 267 =
  35. 35.233 + 298 =
  36. 36.251 + 551 =
  37. 37.470 − 128 =
  38. 38.575 + 344 =
  39. 39.135 + 468 =
  40. 40.505 − 182 =

Answer key

  1. 328
  2. 192
  3. 345
  4. 1205
  5. 165
  6. 746
  7. 719
  8. 153
  9. 1230
  10. 288
  11. 952
  12. 286
  13. 299
  14. 559
  15. 192
  16. 537
  17. 753
  18. 221
  19. 731
  20. 615
  21. 279
  22. 580
  23. 1184
  24. 506
  25. 975
  26. 616
  27. 1043
  28. 221
  29. 588
  30. 541
  31. 434
  32. 317
  33. 912
  34. 254
  35. 531
  36. 802
  37. 342
  38. 919
  39. 603
  40. 323

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