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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 546 · 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. 1.478 + 484 =
  2. 2.639 − 271 =
  3. 3.561 + 439 =
  4. 4.575 + 577 =
  5. 5.486 − 383 =
  6. 6.294 + 256 =
  7. 7.462 + 201 =
  8. 8.657 − 386 =
  9. 9.173 + 423 =
  10. 10.686 − 542 =
  11. 11.874 − 569 =
  12. 12.402 + 384 =
  13. 13.430 + 311 =
  14. 14.148 + 621 =
  15. 15.778 − 341 =
  16. 16.756 + 344 =
  17. 17.164 + 281 =
  18. 18.346 + 491 =
  19. 19.946 − 805 =
  20. 20.291 + 235 =
  21. 21.160 + 491 =
  22. 22.579 − 121 =
  23. 23.445 − 164 =
  24. 24.877 − 342 =
  25. 25.795 − 508 =
  26. 26.630 + 363 =
  27. 27.400 + 338 =
  28. 28.473 − 128 =
  29. 29.571 − 146 =
  30. 30.408 + 387 =
  31. 31.716 + 673 =
  32. 32.289 + 345 =
  33. 33.218 + 616 =
  34. 34.364 + 687 =
  35. 35.903 − 675 =
  36. 36.528 + 398 =
  37. 37.454 + 543 =
  38. 38.665 − 224 =
  39. 39.621 − 181 =
  40. 40.784 + 662 =

Answer key

  1. 962
  2. 368
  3. 1000
  4. 1152
  5. 103
  6. 550
  7. 663
  8. 271
  9. 596
  10. 144
  11. 305
  12. 786
  13. 741
  14. 769
  15. 437
  16. 1100
  17. 445
  18. 837
  19. 141
  20. 526
  21. 651
  22. 458
  23. 281
  24. 535
  25. 287
  26. 993
  27. 738
  28. 345
  29. 425
  30. 795
  31. 1389
  32. 634
  33. 834
  34. 1051
  35. 228
  36. 926
  37. 997
  38. 441
  39. 440
  40. 1446

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