← Add and subtract 3-digit numbers left to right lesson New set →

3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 945 · 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. 1.596 + 481 =
  2. 2.827 − 367 =
  3. 3.377 + 136 =
  4. 4.740 + 475 =
  5. 5.480 − 229 =
  6. 6.970 − 639 =
  7. 7.498 − 386 =
  8. 8.890 − 292 =
  9. 9.541 + 469 =
  10. 10.874 − 297 =
  11. 11.425 + 365 =
  12. 12.983 − 118 =
  13. 13.289 + 594 =
  14. 14.519 + 241 =
  15. 15.744 + 133 =
  16. 16.279 + 181 =
  17. 17.250 + 302 =
  18. 18.522 − 304 =
  19. 19.577 − 251 =
  20. 20.514 + 208 =
  21. 21.473 + 405 =
  22. 22.989 − 811 =
  23. 23.764 + 346 =
  24. 24.395 + 161 =
  25. 25.493 + 348 =
  26. 26.464 − 149 =
  27. 27.540 − 253 =
  28. 28.773 + 352 =
  29. 29.433 − 316 =
  30. 30.863 − 539 =
  31. 31.520 − 392 =
  32. 32.376 + 362 =
  33. 33.611 − 279 =
  34. 34.434 − 137 =
  35. 35.842 − 319 =
  36. 36.787 + 315 =
  37. 37.622 − 445 =
  38. 38.246 + 575 =
  39. 39.523 − 172 =
  40. 40.808 − 648 =

Answer key

  1. 1077
  2. 460
  3. 513
  4. 1215
  5. 251
  6. 331
  7. 112
  8. 598
  9. 1010
  10. 577
  11. 790
  12. 865
  13. 883
  14. 760
  15. 877
  16. 460
  17. 552
  18. 218
  19. 326
  20. 722
  21. 878
  22. 178
  23. 1110
  24. 556
  25. 841
  26. 315
  27. 287
  28. 1125
  29. 117
  30. 324
  31. 128
  32. 738
  33. 332
  34. 297
  35. 523
  36. 1102
  37. 177
  38. 821
  39. 351
  40. 160

Free mental maths lessons, practice and worksheets at talentjr.in/mental-maths