← Add and subtract 3-digit numbers left to right lesson New set →

3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 331 · 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. 1.663 + 384 =
  2. 2.548 + 486 =
  3. 3.460 + 625 =
  4. 4.713 + 498 =
  5. 5.585 + 314 =
  6. 6.447 + 611 =
  7. 7.354 + 466 =
  8. 8.620 − 369 =
  9. 9.555 + 186 =
  10. 10.445 + 279 =
  11. 11.263 + 225 =
  12. 12.553 − 332 =
  13. 13.463 − 202 =
  14. 14.938 − 472 =
  15. 15.780 + 438 =
  16. 16.974 − 549 =
  17. 17.666 − 543 =
  18. 18.169 + 551 =
  19. 19.552 − 412 =
  20. 20.815 − 311 =
  21. 21.463 − 171 =
  22. 22.526 + 518 =
  23. 23.760 − 511 =
  24. 24.643 − 156 =
  25. 25.875 − 296 =
  26. 26.911 − 141 =
  27. 27.465 − 177 =
  28. 28.512 − 117 =
  29. 29.156 + 219 =
  30. 30.200 + 275 =
  31. 31.415 + 412 =
  32. 32.551 − 201 =
  33. 33.184 + 455 =
  34. 34.172 + 611 =
  35. 35.563 − 253 =
  36. 36.419 + 121 =
  37. 37.181 + 401 =
  38. 38.896 − 166 =
  39. 39.985 − 391 =
  40. 40.440 − 122 =

Answer key

  1. 1047
  2. 1034
  3. 1085
  4. 1211
  5. 899
  6. 1058
  7. 820
  8. 251
  9. 741
  10. 724
  11. 488
  12. 221
  13. 261
  14. 466
  15. 1218
  16. 425
  17. 123
  18. 720
  19. 140
  20. 504
  21. 292
  22. 1044
  23. 249
  24. 487
  25. 579
  26. 770
  27. 288
  28. 395
  29. 375
  30. 475
  31. 827
  32. 350
  33. 639
  34. 783
  35. 310
  36. 540
  37. 582
  38. 730
  39. 594
  40. 318

Free mental maths lessons, practice and worksheets at talentjr.in/mental-maths