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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 249 · 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. 1.445 − 173 =
  2. 2.697 + 334 =
  3. 3.745 − 421 =
  4. 4.523 − 302 =
  5. 5.175 + 535 =
  6. 6.782 + 275 =
  7. 7.443 + 247 =
  8. 8.284 + 651 =
  9. 9.352 + 331 =
  10. 10.867 − 598 =
  11. 11.194 + 155 =
  12. 12.767 − 302 =
  13. 13.971 − 147 =
  14. 14.957 − 145 =
  15. 15.230 + 463 =
  16. 16.830 − 428 =
  17. 17.598 − 473 =
  18. 18.771 + 388 =
  19. 19.175 + 542 =
  20. 20.602 + 594 =
  21. 21.437 − 119 =
  22. 22.515 − 286 =
  23. 23.836 − 433 =
  24. 24.701 + 453 =
  25. 25.671 + 234 =
  26. 26.291 + 234 =
  27. 27.727 − 231 =
  28. 28.951 − 333 =
  29. 29.439 − 179 =
  30. 30.948 − 252 =
  31. 31.702 + 183 =
  32. 32.929 − 371 =
  33. 33.497 + 615 =
  34. 34.213 + 665 =
  35. 35.412 + 281 =
  36. 36.610 − 301 =
  37. 37.443 − 198 =
  38. 38.420 + 537 =
  39. 39.550 + 428 =
  40. 40.185 + 258 =

Answer key

  1. 272
  2. 1031
  3. 324
  4. 221
  5. 710
  6. 1057
  7. 690
  8. 935
  9. 683
  10. 269
  11. 349
  12. 465
  13. 824
  14. 812
  15. 693
  16. 402
  17. 125
  18. 1159
  19. 717
  20. 1196
  21. 318
  22. 229
  23. 403
  24. 1154
  25. 905
  26. 525
  27. 496
  28. 618
  29. 260
  30. 696
  31. 885
  32. 558
  33. 1112
  34. 878
  35. 693
  36. 309
  37. 245
  38. 957
  39. 978
  40. 443

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