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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 707 · 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. 1.629 + 193 =
  2. 2.187 + 475 =
  3. 3.319 + 534 =
  4. 4.383 + 133 =
  5. 5.430 + 597 =
  6. 6.399 + 157 =
  7. 7.615 − 121 =
  8. 8.689 + 373 =
  9. 9.826 − 568 =
  10. 10.535 + 153 =
  11. 11.687 + 596 =
  12. 12.498 − 123 =
  13. 13.839 − 453 =
  14. 14.533 + 423 =
  15. 15.826 − 258 =
  16. 16.684 + 493 =
  17. 17.237 + 435 =
  18. 18.708 + 216 =
  19. 19.746 + 669 =
  20. 20.272 + 633 =
  21. 21.173 + 491 =
  22. 22.137 + 468 =
  23. 23.761 + 541 =
  24. 24.387 + 164 =
  25. 25.536 − 283 =
  26. 26.623 − 311 =
  27. 27.155 + 682 =
  28. 28.126 + 214 =
  29. 29.616 + 194 =
  30. 30.644 + 428 =
  31. 31.187 + 345 =
  32. 32.516 − 169 =
  33. 33.447 − 278 =
  34. 34.157 + 481 =
  35. 35.891 − 683 =
  36. 36.662 + 558 =
  37. 37.687 + 563 =
  38. 38.189 + 293 =
  39. 39.582 + 529 =
  40. 40.566 − 184 =

Answer key

  1. 822
  2. 662
  3. 853
  4. 516
  5. 1027
  6. 556
  7. 494
  8. 1062
  9. 258
  10. 688
  11. 1283
  12. 375
  13. 386
  14. 956
  15. 568
  16. 1177
  17. 672
  18. 924
  19. 1415
  20. 905
  21. 664
  22. 605
  23. 1302
  24. 551
  25. 253
  26. 312
  27. 837
  28. 340
  29. 810
  30. 1072
  31. 532
  32. 347
  33. 169
  34. 638
  35. 208
  36. 1220
  37. 1250
  38. 482
  39. 1111
  40. 382

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