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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 722 · 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. 1.617 − 298 =
  2. 2.597 + 278 =
  3. 3.203 + 624 =
  4. 4.470 + 219 =
  5. 5.607 + 618 =
  6. 6.757 + 194 =
  7. 7.536 + 471 =
  8. 8.192 + 262 =
  9. 9.422 − 193 =
  10. 10.243 + 318 =
  11. 11.622 + 204 =
  12. 12.692 + 221 =
  13. 13.544 − 112 =
  14. 14.895 − 525 =
  15. 15.446 − 165 =
  16. 16.587 + 201 =
  17. 17.528 − 334 =
  18. 18.546 + 441 =
  19. 19.147 + 128 =
  20. 20.428 − 234 =
  21. 21.934 − 663 =
  22. 22.976 − 838 =
  23. 23.428 − 231 =
  24. 24.726 − 588 =
  25. 25.422 − 151 =
  26. 26.430 − 239 =
  27. 27.366 + 125 =
  28. 28.741 + 294 =
  29. 29.261 + 505 =
  30. 30.455 + 246 =
  31. 31.631 − 325 =
  32. 32.807 − 701 =
  33. 33.931 − 607 =
  34. 34.149 + 371 =
  35. 35.711 − 166 =
  36. 36.767 − 439 =
  37. 37.565 − 433 =
  38. 38.399 + 437 =
  39. 39.706 − 496 =
  40. 40.494 − 363 =

Answer key

  1. 319
  2. 875
  3. 827
  4. 689
  5. 1225
  6. 951
  7. 1007
  8. 454
  9. 229
  10. 561
  11. 826
  12. 913
  13. 432
  14. 370
  15. 281
  16. 788
  17. 194
  18. 987
  19. 275
  20. 194
  21. 271
  22. 138
  23. 197
  24. 138
  25. 271
  26. 191
  27. 491
  28. 1035
  29. 766
  30. 701
  31. 306
  32. 106
  33. 324
  34. 520
  35. 545
  36. 328
  37. 132
  38. 836
  39. 210
  40. 131

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