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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 715 · 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. 1.165 + 132 =
  2. 2.826 − 654 =
  3. 3.684 + 583 =
  4. 4.141 + 595 =
  5. 5.933 − 377 =
  6. 6.342 + 686 =
  7. 7.716 + 672 =
  8. 8.750 − 255 =
  9. 9.451 + 132 =
  10. 10.657 + 311 =
  11. 11.587 + 231 =
  12. 12.518 + 472 =
  13. 13.663 + 498 =
  14. 14.809 − 174 =
  15. 15.233 + 173 =
  16. 16.544 + 208 =
  17. 17.184 + 112 =
  18. 18.777 − 311 =
  19. 19.535 − 113 =
  20. 20.429 + 362 =
  21. 21.252 + 672 =
  22. 22.632 − 396 =
  23. 23.810 − 667 =
  24. 24.676 + 283 =
  25. 25.487 − 132 =
  26. 26.131 + 495 =
  27. 27.395 + 465 =
  28. 28.445 + 523 =
  29. 29.317 + 371 =
  30. 30.497 + 283 =
  31. 31.740 − 599 =
  32. 32.333 + 223 =
  33. 33.914 − 719 =
  34. 34.947 − 274 =
  35. 35.419 − 173 =
  36. 36.192 + 373 =
  37. 37.416 − 231 =
  38. 38.645 − 331 =
  39. 39.628 + 554 =
  40. 40.751 + 371 =

Answer key

  1. 297
  2. 172
  3. 1267
  4. 736
  5. 556
  6. 1028
  7. 1388
  8. 495
  9. 583
  10. 968
  11. 818
  12. 990
  13. 1161
  14. 635
  15. 406
  16. 752
  17. 296
  18. 466
  19. 422
  20. 791
  21. 924
  22. 236
  23. 143
  24. 959
  25. 355
  26. 626
  27. 860
  28. 968
  29. 688
  30. 780
  31. 141
  32. 556
  33. 195
  34. 673
  35. 246
  36. 565
  37. 185
  38. 314
  39. 1182
  40. 1122

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