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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 448 · 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. 1.716 − 379 =
  2. 2.299 + 371 =
  3. 3.250 + 441 =
  4. 4.940 − 608 =
  5. 5.786 + 192 =
  6. 6.893 − 266 =
  7. 7.280 + 114 =
  8. 8.723 + 573 =
  9. 9.755 − 171 =
  10. 10.662 + 271 =
  11. 11.988 − 228 =
  12. 12.457 − 122 =
  13. 13.711 − 546 =
  14. 14.883 − 148 =
  15. 15.161 + 341 =
  16. 16.488 + 628 =
  17. 17.576 − 173 =
  18. 18.287 + 428 =
  19. 19.220 + 127 =
  20. 20.474 + 464 =
  21. 21.901 − 743 =
  22. 22.153 + 456 =
  23. 23.485 − 251 =
  24. 24.320 + 292 =
  25. 25.515 − 244 =
  26. 26.858 − 614 =
  27. 27.642 − 442 =
  28. 28.610 + 292 =
  29. 29.662 + 219 =
  30. 30.177 + 689 =
  31. 31.135 + 121 =
  32. 32.689 + 284 =
  33. 33.572 + 148 =
  34. 34.443 − 342 =
  35. 35.660 + 624 =
  36. 36.831 − 699 =
  37. 37.548 − 114 =
  38. 38.520 + 591 =
  39. 39.536 − 305 =
  40. 40.136 + 634 =

Answer key

  1. 337
  2. 670
  3. 691
  4. 332
  5. 978
  6. 627
  7. 394
  8. 1296
  9. 584
  10. 933
  11. 760
  12. 335
  13. 165
  14. 735
  15. 502
  16. 1116
  17. 403
  18. 715
  19. 347
  20. 938
  21. 158
  22. 609
  23. 234
  24. 612
  25. 271
  26. 244
  27. 200
  28. 902
  29. 881
  30. 866
  31. 256
  32. 973
  33. 720
  34. 101
  35. 1284
  36. 132
  37. 434
  38. 1111
  39. 231
  40. 770

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