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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 38 · 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. 1.207 + 618 =
  2. 2.498 − 224 =
  3. 3.727 − 227 =
  4. 4.510 + 595 =
  5. 5.930 − 141 =
  6. 6.556 + 399 =
  7. 7.737 + 673 =
  8. 8.687 − 507 =
  9. 9.747 − 502 =
  10. 10.799 − 136 =
  11. 11.253 + 297 =
  12. 12.386 + 306 =
  13. 13.234 + 237 =
  14. 14.511 + 303 =
  15. 15.922 − 224 =
  16. 16.273 + 211 =
  17. 17.371 + 184 =
  18. 18.567 − 185 =
  19. 19.703 − 342 =
  20. 20.433 + 318 =
  21. 21.684 − 324 =
  22. 22.435 + 659 =
  23. 23.517 − 228 =
  24. 24.535 − 138 =
  25. 25.449 + 154 =
  26. 26.379 + 232 =
  27. 27.514 − 323 =
  28. 28.431 − 125 =
  29. 29.782 + 149 =
  30. 30.554 + 561 =
  31. 31.635 + 204 =
  32. 32.965 − 711 =
  33. 33.421 + 306 =
  34. 34.425 + 112 =
  35. 35.675 − 249 =
  36. 36.703 + 318 =
  37. 37.532 − 253 =
  38. 38.582 + 582 =
  39. 39.558 + 126 =
  40. 40.964 − 445 =

Answer key

  1. 825
  2. 274
  3. 500
  4. 1105
  5. 789
  6. 955
  7. 1410
  8. 180
  9. 245
  10. 663
  11. 550
  12. 692
  13. 471
  14. 814
  15. 698
  16. 484
  17. 555
  18. 382
  19. 361
  20. 751
  21. 360
  22. 1094
  23. 289
  24. 397
  25. 603
  26. 611
  27. 191
  28. 306
  29. 931
  30. 1115
  31. 839
  32. 254
  33. 727
  34. 537
  35. 426
  36. 1021
  37. 279
  38. 1164
  39. 684
  40. 519

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