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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 257 · 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. 1.836 − 181 =
  2. 2.300 + 495 =
  3. 3.802 − 342 =
  4. 4.427 − 188 =
  5. 5.757 − 536 =
  6. 6.731 + 227 =
  7. 7.548 − 203 =
  8. 8.614 − 165 =
  9. 9.587 − 448 =
  10. 10.953 − 506 =
  11. 11.740 − 398 =
  12. 12.880 − 307 =
  13. 13.662 + 191 =
  14. 14.917 − 257 =
  15. 15.568 − 145 =
  16. 16.826 − 206 =
  17. 17.482 + 653 =
  18. 18.485 + 618 =
  19. 19.589 + 241 =
  20. 20.769 + 283 =
  21. 21.676 + 476 =
  22. 22.607 + 567 =
  23. 23.639 + 467 =
  24. 24.494 + 115 =
  25. 25.201 + 241 =
  26. 26.228 + 382 =
  27. 27.380 + 279 =
  28. 28.351 + 325 =
  29. 29.744 − 297 =
  30. 30.744 + 486 =
  31. 31.813 − 553 =
  32. 32.634 − 248 =
  33. 33.736 + 527 =
  34. 34.194 + 198 =
  35. 35.671 + 417 =
  36. 36.435 − 164 =
  37. 37.619 + 491 =
  38. 38.312 + 295 =
  39. 39.485 + 667 =
  40. 40.743 − 377 =

Answer key

  1. 655
  2. 795
  3. 460
  4. 239
  5. 221
  6. 958
  7. 345
  8. 449
  9. 139
  10. 447
  11. 342
  12. 573
  13. 853
  14. 660
  15. 423
  16. 620
  17. 1135
  18. 1103
  19. 830
  20. 1052
  21. 1152
  22. 1174
  23. 1106
  24. 609
  25. 442
  26. 610
  27. 659
  28. 676
  29. 447
  30. 1230
  31. 260
  32. 386
  33. 1263
  34. 392
  35. 1088
  36. 271
  37. 1110
  38. 607
  39. 1152
  40. 366

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