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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 457 · 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. 1.166 + 342 =
  2. 2.766 + 132 =
  3. 3.683 + 199 =
  4. 4.663 + 161 =
  5. 5.392 + 163 =
  6. 6.568 + 191 =
  7. 7.514 − 292 =
  8. 8.740 − 199 =
  9. 9.433 − 222 =
  10. 10.391 + 348 =
  11. 11.218 + 464 =
  12. 12.456 + 653 =
  13. 13.981 − 401 =
  14. 14.871 − 267 =
  15. 15.130 + 423 =
  16. 16.446 + 564 =
  17. 17.703 − 218 =
  18. 18.355 + 211 =
  19. 19.556 + 683 =
  20. 20.674 + 189 =
  21. 21.634 + 214 =
  22. 22.684 − 272 =
  23. 23.540 − 114 =
  24. 24.984 − 288 =
  25. 25.599 − 251 =
  26. 26.479 + 644 =
  27. 27.989 − 786 =
  28. 28.561 + 157 =
  29. 29.197 + 177 =
  30. 30.527 − 256 =
  31. 31.551 + 349 =
  32. 32.504 + 447 =
  33. 33.944 − 649 =
  34. 34.401 + 126 =
  35. 35.542 − 241 =
  36. 36.684 − 114 =
  37. 37.270 + 442 =
  38. 38.712 − 363 =
  39. 39.722 + 321 =
  40. 40.129 + 472 =

Answer key

  1. 508
  2. 898
  3. 882
  4. 824
  5. 555
  6. 759
  7. 222
  8. 541
  9. 211
  10. 739
  11. 682
  12. 1109
  13. 580
  14. 604
  15. 553
  16. 1010
  17. 485
  18. 566
  19. 1239
  20. 863
  21. 848
  22. 412
  23. 426
  24. 696
  25. 348
  26. 1123
  27. 203
  28. 718
  29. 374
  30. 271
  31. 900
  32. 951
  33. 295
  34. 527
  35. 301
  36. 570
  37. 712
  38. 349
  39. 1043
  40. 601

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