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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 737 · 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. 1.699 − 544 =
  2. 2.951 − 137 =
  3. 3.581 + 189 =
  4. 4.262 + 421 =
  5. 5.818 − 681 =
  6. 6.568 + 672 =
  7. 7.682 − 219 =
  8. 8.442 − 141 =
  9. 9.817 − 564 =
  10. 10.123 + 439 =
  11. 11.569 + 684 =
  12. 12.983 − 151 =
  13. 13.392 + 683 =
  14. 14.415 + 215 =
  15. 15.551 − 202 =
  16. 16.636 + 375 =
  17. 17.679 + 199 =
  18. 18.528 − 422 =
  19. 19.299 + 151 =
  20. 20.241 + 268 =
  21. 21.709 − 127 =
  22. 22.718 + 465 =
  23. 23.705 + 668 =
  24. 24.774 − 143 =
  25. 25.705 − 396 =
  26. 26.267 + 596 =
  27. 27.150 + 264 =
  28. 28.588 + 343 =
  29. 29.203 + 623 =
  30. 30.388 + 651 =
  31. 31.723 − 368 =
  32. 32.707 + 419 =
  33. 33.587 + 446 =
  34. 34.464 − 193 =
  35. 35.271 + 518 =
  36. 36.970 − 275 =
  37. 37.130 + 313 =
  38. 38.748 − 426 =
  39. 39.320 + 569 =
  40. 40.638 − 391 =

Answer key

  1. 155
  2. 814
  3. 770
  4. 683
  5. 137
  6. 1240
  7. 463
  8. 301
  9. 253
  10. 562
  11. 1253
  12. 832
  13. 1075
  14. 630
  15. 349
  16. 1011
  17. 878
  18. 106
  19. 450
  20. 509
  21. 582
  22. 1183
  23. 1373
  24. 631
  25. 309
  26. 863
  27. 414
  28. 931
  29. 826
  30. 1039
  31. 355
  32. 1126
  33. 1033
  34. 271
  35. 789
  36. 695
  37. 443
  38. 322
  39. 889
  40. 247

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