← 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 47 · 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. 1.578 + 511 =
  2. 2.443 − 124 =
  3. 3.158 + 581 =
  4. 4.547 + 471 =
  5. 5.480 − 239 =
  6. 6.344 + 259 =
  7. 7.439 − 145 =
  8. 8.227 + 477 =
  9. 9.514 + 199 =
  10. 10.214 + 247 =
  11. 11.191 + 488 =
  12. 12.414 − 308 =
  13. 13.465 − 248 =
  14. 14.953 − 786 =
  15. 15.554 + 215 =
  16. 16.679 − 202 =
  17. 17.203 + 131 =
  18. 18.131 + 169 =
  19. 19.622 + 651 =
  20. 20.628 − 494 =
  21. 21.784 − 405 =
  22. 22.840 − 319 =
  23. 23.337 + 378 =
  24. 24.491 − 155 =
  25. 25.485 + 236 =
  26. 26.779 − 185 =
  27. 27.428 − 153 =
  28. 28.498 − 392 =
  29. 29.130 + 679 =
  30. 30.703 − 436 =
  31. 31.896 − 667 =
  32. 32.654 + 202 =
  33. 33.563 − 403 =
  34. 34.735 + 528 =
  35. 35.513 − 141 =
  36. 36.432 − 279 =
  37. 37.574 + 326 =
  38. 38.126 + 325 =
  39. 39.732 − 333 =
  40. 40.952 − 344 =

Answer key

  1. 1089
  2. 319
  3. 739
  4. 1018
  5. 241
  6. 603
  7. 294
  8. 704
  9. 713
  10. 461
  11. 679
  12. 106
  13. 217
  14. 167
  15. 769
  16. 477
  17. 334
  18. 300
  19. 1273
  20. 134
  21. 379
  22. 521
  23. 715
  24. 336
  25. 721
  26. 594
  27. 275
  28. 106
  29. 809
  30. 267
  31. 229
  32. 856
  33. 160
  34. 1263
  35. 372
  36. 153
  37. 900
  38. 451
  39. 399
  40. 608

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