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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 608 · 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. 1.514 − 336 =
  2. 2.566 − 229 =
  3. 3.253 + 604 =
  4. 4.743 + 339 =
  5. 5.199 + 235 =
  6. 6.195 + 258 =
  7. 7.907 − 526 =
  8. 8.719 + 258 =
  9. 9.351 + 199 =
  10. 10.522 + 131 =
  11. 11.231 + 613 =
  12. 12.201 + 215 =
  13. 13.303 + 557 =
  14. 14.191 + 463 =
  15. 15.630 + 363 =
  16. 16.414 − 119 =
  17. 17.784 + 294 =
  18. 18.218 + 553 =
  19. 19.457 + 143 =
  20. 20.246 + 266 =
  21. 21.281 + 411 =
  22. 22.700 + 187 =
  23. 23.617 − 206 =
  24. 24.719 − 217 =
  25. 25.837 − 347 =
  26. 26.201 + 664 =
  27. 27.325 + 554 =
  28. 28.209 + 192 =
  29. 29.652 − 155 =
  30. 30.813 − 375 =
  31. 31.524 − 211 =
  32. 32.763 + 335 =
  33. 33.634 − 421 =
  34. 34.748 + 196 =
  35. 35.554 + 172 =
  36. 36.597 + 621 =
  37. 37.507 + 235 =
  38. 38.849 − 611 =
  39. 39.821 − 353 =
  40. 40.639 − 208 =

Answer key

  1. 178
  2. 337
  3. 857
  4. 1082
  5. 434
  6. 453
  7. 381
  8. 977
  9. 550
  10. 653
  11. 844
  12. 416
  13. 860
  14. 654
  15. 993
  16. 295
  17. 1078
  18. 771
  19. 600
  20. 512
  21. 692
  22. 887
  23. 411
  24. 502
  25. 490
  26. 865
  27. 879
  28. 401
  29. 497
  30. 438
  31. 313
  32. 1098
  33. 213
  34. 944
  35. 726
  36. 1218
  37. 742
  38. 238
  39. 468
  40. 431

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