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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 316 · 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. 1.664 + 233 =
  2. 2.676 − 291 =
  3. 3.452 + 243 =
  4. 4.742 − 202 =
  5. 5.771 + 412 =
  6. 6.439 + 217 =
  7. 7.413 + 146 =
  8. 8.539 − 182 =
  9. 9.928 − 504 =
  10. 10.454 + 238 =
  11. 11.942 − 655 =
  12. 12.760 − 589 =
  13. 13.709 − 213 =
  14. 14.404 + 225 =
  15. 15.430 − 271 =
  16. 16.429 + 482 =
  17. 17.868 − 451 =
  18. 18.720 − 425 =
  19. 19.181 + 461 =
  20. 20.587 + 222 =
  21. 21.209 + 647 =
  22. 22.699 + 226 =
  23. 23.206 + 215 =
  24. 24.371 + 114 =
  25. 25.300 + 272 =
  26. 26.406 + 315 =
  27. 27.682 − 199 =
  28. 28.529 − 183 =
  29. 29.742 − 599 =
  30. 30.751 − 399 =
  31. 31.225 + 122 =
  32. 32.473 + 504 =
  33. 33.604 − 121 =
  34. 34.435 − 261 =
  35. 35.495 + 468 =
  36. 36.812 − 366 =
  37. 37.642 − 471 =
  38. 38.824 − 465 =
  39. 39.702 + 395 =
  40. 40.162 + 161 =

Answer key

  1. 897
  2. 385
  3. 695
  4. 540
  5. 1183
  6. 656
  7. 559
  8. 357
  9. 424
  10. 692
  11. 287
  12. 171
  13. 496
  14. 629
  15. 159
  16. 911
  17. 417
  18. 295
  19. 642
  20. 809
  21. 856
  22. 925
  23. 421
  24. 485
  25. 572
  26. 721
  27. 483
  28. 346
  29. 143
  30. 352
  31. 347
  32. 977
  33. 483
  34. 174
  35. 963
  36. 446
  37. 171
  38. 359
  39. 1097
  40. 323

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