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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 291 · 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. 1.470 + 203 =
  2. 2.156 + 581 =
  3. 3.671 + 434 =
  4. 4.737 − 293 =
  5. 5.401 + 511 =
  6. 6.148 + 201 =
  7. 7.752 − 241 =
  8. 8.173 + 675 =
  9. 9.850 − 446 =
  10. 10.793 − 465 =
  11. 11.253 + 453 =
  12. 12.508 − 181 =
  13. 13.751 − 333 =
  14. 14.127 + 662 =
  15. 15.760 − 354 =
  16. 16.542 + 172 =
  17. 17.447 − 181 =
  18. 18.510 + 519 =
  19. 19.307 + 217 =
  20. 20.694 + 256 =
  21. 21.636 − 371 =
  22. 22.644 − 461 =
  23. 23.757 + 293 =
  24. 24.436 + 306 =
  25. 25.428 − 206 =
  26. 26.920 − 174 =
  27. 27.832 − 565 =
  28. 28.792 − 403 =
  29. 29.171 + 274 =
  30. 30.777 + 156 =
  31. 31.514 − 341 =
  32. 32.723 + 339 =
  33. 33.424 + 585 =
  34. 34.434 + 231 =
  35. 35.616 + 572 =
  36. 36.593 + 639 =
  37. 37.946 − 698 =
  38. 38.710 + 451 =
  39. 39.599 − 324 =
  40. 40.250 + 571 =

Answer key

  1. 673
  2. 737
  3. 1105
  4. 444
  5. 912
  6. 349
  7. 511
  8. 848
  9. 404
  10. 328
  11. 706
  12. 327
  13. 418
  14. 789
  15. 406
  16. 714
  17. 266
  18. 1029
  19. 524
  20. 950
  21. 265
  22. 183
  23. 1050
  24. 742
  25. 222
  26. 746
  27. 267
  28. 389
  29. 445
  30. 933
  31. 173
  32. 1062
  33. 1009
  34. 665
  35. 1188
  36. 1232
  37. 248
  38. 1161
  39. 275
  40. 821

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