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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 753 · 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. 1.198 + 153 =
  2. 2.838 − 388 =
  3. 3.809 − 651 =
  4. 4.765 − 519 =
  5. 5.481 + 186 =
  6. 6.548 + 686 =
  7. 7.763 − 423 =
  8. 8.406 + 683 =
  9. 9.647 − 468 =
  10. 10.951 − 761 =
  11. 11.651 + 317 =
  12. 12.412 − 157 =
  13. 13.207 + 284 =
  14. 14.509 + 372 =
  15. 15.898 − 712 =
  16. 16.572 + 134 =
  17. 17.494 − 143 =
  18. 18.255 + 271 =
  19. 19.346 + 292 =
  20. 20.904 − 516 =
  21. 21.376 + 251 =
  22. 22.394 + 638 =
  23. 23.389 + 394 =
  24. 24.140 + 493 =
  25. 25.582 + 231 =
  26. 26.443 + 619 =
  27. 27.591 + 403 =
  28. 28.654 − 309 =
  29. 29.383 + 588 =
  30. 30.380 + 254 =
  31. 31.353 + 372 =
  32. 32.285 + 569 =
  33. 33.201 + 254 =
  34. 34.620 + 254 =
  35. 35.472 + 432 =
  36. 36.791 − 282 =
  37. 37.657 + 615 =
  38. 38.758 + 151 =
  39. 39.745 + 252 =
  40. 40.749 + 295 =

Answer key

  1. 351
  2. 450
  3. 158
  4. 246
  5. 667
  6. 1234
  7. 340
  8. 1089
  9. 179
  10. 190
  11. 968
  12. 255
  13. 491
  14. 881
  15. 186
  16. 706
  17. 351
  18. 526
  19. 638
  20. 388
  21. 627
  22. 1032
  23. 783
  24. 633
  25. 813
  26. 1062
  27. 994
  28. 345
  29. 971
  30. 634
  31. 725
  32. 854
  33. 455
  34. 874
  35. 904
  36. 509
  37. 1272
  38. 909
  39. 997
  40. 1044

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