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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 202 · 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. 1.218 + 362 =
  2. 2.691 − 347 =
  3. 3.802 − 374 =
  4. 4.144 + 574 =
  5. 5.801 − 279 =
  6. 6.578 + 195 =
  7. 7.541 − 171 =
  8. 8.267 + 554 =
  9. 9.225 + 283 =
  10. 10.604 − 224 =
  11. 11.243 + 344 =
  12. 12.449 − 153 =
  13. 13.780 + 256 =
  14. 14.581 + 192 =
  15. 15.627 − 272 =
  16. 16.747 − 221 =
  17. 17.767 + 566 =
  18. 18.145 + 152 =
  19. 19.467 − 134 =
  20. 20.417 − 303 =
  21. 21.755 + 386 =
  22. 22.628 + 458 =
  23. 23.735 + 561 =
  24. 24.754 + 391 =
  25. 25.958 − 597 =
  26. 26.229 + 601 =
  27. 27.452 + 169 =
  28. 28.286 + 624 =
  29. 29.394 + 153 =
  30. 30.715 + 595 =
  31. 31.217 + 593 =
  32. 32.210 + 182 =
  33. 33.221 + 397 =
  34. 34.703 − 213 =
  35. 35.360 + 361 =
  36. 36.432 + 448 =
  37. 37.480 − 359 =
  38. 38.394 + 175 =
  39. 39.445 + 171 =
  40. 40.509 − 157 =

Answer key

  1. 580
  2. 344
  3. 428
  4. 718
  5. 522
  6. 773
  7. 370
  8. 821
  9. 508
  10. 380
  11. 587
  12. 296
  13. 1036
  14. 773
  15. 355
  16. 526
  17. 1333
  18. 297
  19. 333
  20. 114
  21. 1141
  22. 1086
  23. 1296
  24. 1145
  25. 361
  26. 830
  27. 621
  28. 910
  29. 547
  30. 1310
  31. 810
  32. 392
  33. 618
  34. 490
  35. 721
  36. 880
  37. 121
  38. 569
  39. 616
  40. 352

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