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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 487 · 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. 1.159 + 132 =
  2. 2.878 − 613 =
  3. 3.365 + 595 =
  4. 4.569 − 441 =
  5. 5.444 + 119 =
  6. 6.858 − 305 =
  7. 7.725 − 181 =
  8. 8.526 + 528 =
  9. 9.768 − 376 =
  10. 10.573 + 468 =
  11. 11.535 − 431 =
  12. 12.909 − 211 =
  13. 13.376 + 199 =
  14. 14.908 − 621 =
  15. 15.769 + 649 =
  16. 16.972 − 658 =
  17. 17.941 − 695 =
  18. 18.971 − 124 =
  19. 19.947 − 261 =
  20. 20.523 − 151 =
  21. 21.237 + 647 =
  22. 22.576 − 131 =
  23. 23.388 + 236 =
  24. 24.734 − 621 =
  25. 25.722 − 295 =
  26. 26.946 − 832 =
  27. 27.201 + 245 =
  28. 28.154 + 487 =
  29. 29.757 + 145 =
  30. 30.608 − 376 =
  31. 31.696 + 284 =
  32. 32.751 + 428 =
  33. 33.664 + 611 =
  34. 34.246 + 598 =
  35. 35.737 + 243 =
  36. 36.722 + 353 =
  37. 37.276 + 282 =
  38. 38.151 + 265 =
  39. 39.258 + 523 =
  40. 40.192 + 157 =

Answer key

  1. 291
  2. 265
  3. 960
  4. 128
  5. 563
  6. 553
  7. 544
  8. 1054
  9. 392
  10. 1041
  11. 104
  12. 698
  13. 575
  14. 287
  15. 1418
  16. 314
  17. 246
  18. 847
  19. 686
  20. 372
  21. 884
  22. 445
  23. 624
  24. 113
  25. 427
  26. 114
  27. 446
  28. 641
  29. 902
  30. 232
  31. 980
  32. 1179
  33. 1275
  34. 844
  35. 980
  36. 1075
  37. 558
  38. 416
  39. 781
  40. 349

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