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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 860 · 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. 1.702 + 221 =
  2. 2.253 + 628 =
  3. 3.704 − 278 =
  4. 4.714 − 601 =
  5. 5.584 − 171 =
  6. 6.404 + 272 =
  7. 7.730 − 511 =
  8. 8.415 − 221 =
  9. 9.980 − 566 =
  10. 10.214 + 616 =
  11. 11.456 + 475 =
  12. 12.444 − 276 =
  13. 13.762 + 142 =
  14. 14.245 + 284 =
  15. 15.429 + 455 =
  16. 16.452 − 292 =
  17. 17.509 − 188 =
  18. 18.880 − 451 =
  19. 19.729 − 265 =
  20. 20.301 + 292 =
  21. 21.783 + 116 =
  22. 22.385 + 596 =
  23. 23.759 − 623 =
  24. 24.963 − 267 =
  25. 25.805 − 563 =
  26. 26.644 − 152 =
  27. 27.417 − 241 =
  28. 28.765 − 529 =
  29. 29.614 + 318 =
  30. 30.565 + 545 =
  31. 31.487 − 323 =
  32. 32.362 + 683 =
  33. 33.729 − 465 =
  34. 34.202 + 377 =
  35. 35.541 − 136 =
  36. 36.681 + 666 =
  37. 37.425 − 151 =
  38. 38.473 + 463 =
  39. 39.305 + 592 =
  40. 40.874 − 194 =

Answer key

  1. 923
  2. 881
  3. 426
  4. 113
  5. 413
  6. 676
  7. 219
  8. 194
  9. 414
  10. 830
  11. 931
  12. 168
  13. 904
  14. 529
  15. 884
  16. 160
  17. 321
  18. 429
  19. 464
  20. 593
  21. 899
  22. 981
  23. 136
  24. 696
  25. 242
  26. 492
  27. 176
  28. 236
  29. 932
  30. 1110
  31. 164
  32. 1045
  33. 264
  34. 579
  35. 405
  36. 1347
  37. 274
  38. 936
  39. 897
  40. 680

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