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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 290 · 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. 1.689 − 407 =
  2. 2.261 + 437 =
  3. 3.779 − 348 =
  4. 4.448 − 122 =
  5. 5.982 − 334 =
  6. 6.683 − 248 =
  7. 7.620 + 422 =
  8. 8.846 − 709 =
  9. 9.520 − 269 =
  10. 10.799 − 528 =
  11. 11.776 − 247 =
  12. 12.609 + 558 =
  13. 13.503 + 639 =
  14. 14.280 + 526 =
  15. 15.691 − 316 =
  16. 16.936 − 604 =
  17. 17.252 + 487 =
  18. 18.177 + 224 =
  19. 19.411 + 162 =
  20. 20.270 + 416 =
  21. 21.651 + 386 =
  22. 22.648 + 211 =
  23. 23.474 + 425 =
  24. 24.774 + 471 =
  25. 25.868 − 208 =
  26. 26.434 − 116 =
  27. 27.127 + 525 =
  28. 28.315 + 426 =
  29. 29.770 − 599 =
  30. 30.271 + 503 =
  31. 31.505 − 148 =
  32. 32.452 + 284 =
  33. 33.164 + 554 =
  34. 34.423 + 142 =
  35. 35.131 + 658 =
  36. 36.914 − 134 =
  37. 37.440 + 279 =
  38. 38.748 + 544 =
  39. 39.186 + 417 =
  40. 40.829 − 261 =

Answer key

  1. 282
  2. 698
  3. 431
  4. 326
  5. 648
  6. 435
  7. 1042
  8. 137
  9. 251
  10. 271
  11. 529
  12. 1167
  13. 1142
  14. 806
  15. 375
  16. 332
  17. 739
  18. 401
  19. 573
  20. 686
  21. 1037
  22. 859
  23. 899
  24. 1245
  25. 660
  26. 318
  27. 652
  28. 741
  29. 171
  30. 774
  31. 357
  32. 736
  33. 718
  34. 565
  35. 789
  36. 780
  37. 719
  38. 1292
  39. 603
  40. 568

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