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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 705 · 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. 1.475 − 309 =
  2. 2.612 + 201 =
  3. 3.205 + 442 =
  4. 4.677 − 291 =
  5. 5.505 + 407 =
  6. 6.331 + 595 =
  7. 7.395 + 197 =
  8. 8.567 + 341 =
  9. 9.657 − 293 =
  10. 10.358 + 217 =
  11. 11.709 + 623 =
  12. 12.623 − 356 =
  13. 13.933 − 708 =
  14. 14.248 + 121 =
  15. 15.586 − 483 =
  16. 16.320 + 156 =
  17. 17.909 − 766 =
  18. 18.909 − 601 =
  19. 19.478 − 117 =
  20. 20.436 + 253 =
  21. 21.547 − 302 =
  22. 22.768 + 219 =
  23. 23.682 + 123 =
  24. 24.417 − 189 =
  25. 25.612 − 417 =
  26. 26.807 − 158 =
  27. 27.168 + 408 =
  28. 28.436 + 441 =
  29. 29.787 + 328 =
  30. 30.592 + 392 =
  31. 31.233 + 296 =
  32. 32.517 − 152 =
  33. 33.527 − 281 =
  34. 34.480 + 235 =
  35. 35.231 + 114 =
  36. 36.151 + 582 =
  37. 37.588 + 412 =
  38. 38.417 + 562 =
  39. 39.178 + 678 =
  40. 40.172 + 472 =

Answer key

  1. 166
  2. 813
  3. 647
  4. 386
  5. 912
  6. 926
  7. 592
  8. 908
  9. 364
  10. 575
  11. 1332
  12. 267
  13. 225
  14. 369
  15. 103
  16. 476
  17. 143
  18. 308
  19. 361
  20. 689
  21. 245
  22. 987
  23. 805
  24. 228
  25. 195
  26. 649
  27. 576
  28. 877
  29. 1115
  30. 984
  31. 529
  32. 365
  33. 246
  34. 715
  35. 345
  36. 733
  37. 1000
  38. 979
  39. 856
  40. 644

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