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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 517 · 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. 1.165 + 441 =
  2. 2.212 + 171 =
  3. 3.983 − 769 =
  4. 4.381 + 441 =
  5. 5.354 + 516 =
  6. 6.520 − 307 =
  7. 7.290 + 321 =
  8. 8.729 − 121 =
  9. 9.945 − 508 =
  10. 10.574 − 185 =
  11. 11.618 + 548 =
  12. 12.343 + 499 =
  13. 13.333 + 356 =
  14. 14.690 − 337 =
  15. 15.513 + 135 =
  16. 16.933 − 312 =
  17. 17.614 − 176 =
  18. 18.967 − 826 =
  19. 19.668 + 399 =
  20. 20.782 + 147 =
  21. 21.246 + 191 =
  22. 22.483 + 436 =
  23. 23.354 + 651 =
  24. 24.442 + 367 =
  25. 25.765 + 457 =
  26. 26.740 + 411 =
  27. 27.856 − 557 =
  28. 28.679 + 186 =
  29. 29.634 + 563 =
  30. 30.754 + 542 =
  31. 31.735 + 636 =
  32. 32.578 + 631 =
  33. 33.204 + 655 =
  34. 34.478 − 252 =
  35. 35.626 + 582 =
  36. 36.639 + 311 =
  37. 37.506 + 171 =
  38. 38.950 − 405 =
  39. 39.199 + 468 =
  40. 40.757 + 545 =

Answer key

  1. 606
  2. 383
  3. 214
  4. 822
  5. 870
  6. 213
  7. 611
  8. 608
  9. 437
  10. 389
  11. 1166
  12. 842
  13. 689
  14. 353
  15. 648
  16. 621
  17. 438
  18. 141
  19. 1067
  20. 929
  21. 437
  22. 919
  23. 1005
  24. 809
  25. 1222
  26. 1151
  27. 299
  28. 865
  29. 1197
  30. 1296
  31. 1371
  32. 1209
  33. 859
  34. 226
  35. 1208
  36. 950
  37. 677
  38. 545
  39. 667
  40. 1302

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