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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 664 · 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. 1.732 + 207 =
  2. 2.658 + 647 =
  3. 3.710 − 577 =
  4. 4.315 + 312 =
  5. 5.772 + 235 =
  6. 6.570 − 148 =
  7. 7.309 + 607 =
  8. 8.151 + 673 =
  9. 9.896 − 384 =
  10. 10.752 + 351 =
  11. 11.258 + 178 =
  12. 12.804 − 258 =
  13. 13.416 + 235 =
  14. 14.848 − 536 =
  15. 15.792 − 478 =
  16. 16.622 + 143 =
  17. 17.587 − 219 =
  18. 18.650 + 268 =
  19. 19.255 + 449 =
  20. 20.627 − 527 =
  21. 21.237 + 531 =
  22. 22.490 − 327 =
  23. 23.357 + 488 =
  24. 24.616 − 404 =
  25. 25.248 + 188 =
  26. 26.227 + 274 =
  27. 27.415 − 162 =
  28. 28.776 − 592 =
  29. 29.672 + 551 =
  30. 30.610 + 592 =
  31. 31.531 − 311 =
  32. 32.503 − 275 =
  33. 33.516 − 213 =
  34. 34.660 − 323 =
  35. 35.762 − 241 =
  36. 36.760 + 359 =
  37. 37.451 − 121 =
  38. 38.644 − 433 =
  39. 39.804 − 334 =
  40. 40.267 + 671 =

Answer key

  1. 939
  2. 1305
  3. 133
  4. 627
  5. 1007
  6. 422
  7. 916
  8. 824
  9. 512
  10. 1103
  11. 436
  12. 546
  13. 651
  14. 312
  15. 314
  16. 765
  17. 368
  18. 918
  19. 704
  20. 100
  21. 768
  22. 163
  23. 845
  24. 212
  25. 436
  26. 501
  27. 253
  28. 184
  29. 1223
  30. 1202
  31. 220
  32. 228
  33. 303
  34. 337
  35. 521
  36. 1119
  37. 330
  38. 211
  39. 470
  40. 938

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