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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 625 · 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. 1.486 − 197 =
  2. 2.983 − 611 =
  3. 3.572 − 305 =
  4. 4.253 + 172 =
  5. 5.346 + 681 =
  6. 6.163 + 269 =
  7. 7.786 − 214 =
  8. 8.287 + 273 =
  9. 9.330 + 339 =
  10. 10.591 + 301 =
  11. 11.423 + 175 =
  12. 12.239 + 665 =
  13. 13.723 + 132 =
  14. 14.576 + 214 =
  15. 15.800 − 298 =
  16. 16.277 + 281 =
  17. 17.570 − 201 =
  18. 18.149 + 529 =
  19. 19.695 − 536 =
  20. 20.262 + 285 =
  21. 21.697 − 232 =
  22. 22.628 + 114 =
  23. 23.125 + 169 =
  24. 24.558 + 139 =
  25. 25.607 − 441 =
  26. 26.953 − 121 =
  27. 27.724 + 342 =
  28. 28.963 − 293 =
  29. 29.141 + 181 =
  30. 30.767 − 561 =
  31. 31.235 + 547 =
  32. 32.548 − 319 =
  33. 33.176 + 228 =
  34. 34.309 + 329 =
  35. 35.638 + 126 =
  36. 36.266 + 441 =
  37. 37.149 + 317 =
  38. 38.706 − 567 =
  39. 39.534 − 301 =
  40. 40.397 + 172 =

Answer key

  1. 289
  2. 372
  3. 267
  4. 425
  5. 1027
  6. 432
  7. 572
  8. 560
  9. 669
  10. 892
  11. 598
  12. 904
  13. 855
  14. 790
  15. 502
  16. 558
  17. 369
  18. 678
  19. 159
  20. 547
  21. 465
  22. 742
  23. 294
  24. 697
  25. 166
  26. 832
  27. 1066
  28. 670
  29. 322
  30. 206
  31. 782
  32. 229
  33. 404
  34. 638
  35. 764
  36. 707
  37. 466
  38. 139
  39. 233
  40. 569

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