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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 757 · 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. 1.673 + 241 =
  2. 2.178 + 661 =
  3. 3.777 − 324 =
  4. 4.701 + 244 =
  5. 5.342 + 134 =
  6. 6.548 − 282 =
  7. 7.579 − 202 =
  8. 8.875 − 746 =
  9. 9.402 + 151 =
  10. 10.905 − 274 =
  11. 11.937 − 183 =
  12. 12.949 − 169 =
  13. 13.154 + 307 =
  14. 14.157 + 559 =
  15. 15.608 + 504 =
  16. 16.777 − 192 =
  17. 17.870 − 184 =
  18. 18.540 − 212 =
  19. 19.671 + 196 =
  20. 20.617 + 324 =
  21. 21.563 + 286 =
  22. 22.164 + 162 =
  23. 23.608 − 114 =
  24. 24.570 + 661 =
  25. 25.541 + 175 =
  26. 26.762 + 228 =
  27. 27.376 + 236 =
  28. 28.911 − 333 =
  29. 29.146 + 235 =
  30. 30.470 + 602 =
  31. 31.613 + 433 =
  32. 32.458 − 216 =
  33. 33.422 + 574 =
  34. 34.690 − 467 =
  35. 35.285 + 526 =
  36. 36.542 − 183 =
  37. 37.363 + 383 =
  38. 38.542 + 602 =
  39. 39.528 − 331 =
  40. 40.539 − 283 =

Answer key

  1. 914
  2. 839
  3. 453
  4. 945
  5. 476
  6. 266
  7. 377
  8. 129
  9. 553
  10. 631
  11. 754
  12. 780
  13. 461
  14. 716
  15. 1112
  16. 585
  17. 686
  18. 328
  19. 867
  20. 941
  21. 849
  22. 326
  23. 494
  24. 1231
  25. 716
  26. 990
  27. 612
  28. 578
  29. 381
  30. 1072
  31. 1046
  32. 242
  33. 996
  34. 223
  35. 811
  36. 359
  37. 746
  38. 1144
  39. 197
  40. 256

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