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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 665 · 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. 1.459 − 158 =
  2. 2.820 − 279 =
  3. 3.673 − 436 =
  4. 4.126 + 408 =
  5. 5.312 + 231 =
  6. 6.700 − 578 =
  7. 7.506 + 273 =
  8. 8.221 + 335 =
  9. 9.465 + 118 =
  10. 10.398 + 297 =
  11. 11.841 − 276 =
  12. 12.545 − 403 =
  13. 13.727 − 315 =
  14. 14.723 − 525 =
  15. 15.570 − 117 =
  16. 16.600 − 217 =
  17. 17.845 − 426 =
  18. 18.132 + 182 =
  19. 19.594 + 403 =
  20. 20.800 − 404 =
  21. 21.571 − 132 =
  22. 22.490 + 511 =
  23. 23.458 + 207 =
  24. 24.325 + 182 =
  25. 25.418 − 229 =
  26. 26.233 + 225 =
  27. 27.689 + 525 =
  28. 28.686 + 362 =
  29. 29.332 + 657 =
  30. 30.588 − 384 =
  31. 31.719 − 431 =
  32. 32.236 + 288 =
  33. 33.317 + 527 =
  34. 34.364 + 169 =
  35. 35.760 + 194 =
  36. 36.827 − 376 =
  37. 37.974 − 541 =
  38. 38.798 − 482 =
  39. 39.561 − 411 =
  40. 40.544 − 434 =

Answer key

  1. 301
  2. 541
  3. 237
  4. 534
  5. 543
  6. 122
  7. 779
  8. 556
  9. 583
  10. 695
  11. 565
  12. 142
  13. 412
  14. 198
  15. 453
  16. 383
  17. 419
  18. 314
  19. 997
  20. 396
  21. 439
  22. 1001
  23. 665
  24. 507
  25. 189
  26. 458
  27. 1214
  28. 1048
  29. 989
  30. 204
  31. 288
  32. 524
  33. 844
  34. 533
  35. 954
  36. 451
  37. 433
  38. 316
  39. 150
  40. 110

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