← 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 857 · 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. 1.475 − 351 =
  2. 2.186 + 633 =
  3. 3.520 + 612 =
  4. 4.271 + 267 =
  5. 5.473 + 649 =
  6. 6.858 − 753 =
  7. 7.912 − 162 =
  8. 8.750 + 207 =
  9. 9.692 + 397 =
  10. 10.746 + 397 =
  11. 11.601 − 297 =
  12. 12.578 − 304 =
  13. 13.897 − 576 =
  14. 14.254 + 158 =
  15. 15.679 − 453 =
  16. 16.928 − 375 =
  17. 17.368 + 584 =
  18. 18.512 − 285 =
  19. 19.699 − 509 =
  20. 20.943 − 619 =
  21. 21.503 − 301 =
  22. 22.944 − 246 =
  23. 23.902 − 608 =
  24. 24.419 + 633 =
  25. 25.231 + 501 =
  26. 26.725 − 163 =
  27. 27.804 − 244 =
  28. 28.747 + 521 =
  29. 29.655 − 207 =
  30. 30.822 − 364 =
  31. 31.311 + 576 =
  32. 32.978 − 867 =
  33. 33.525 − 392 =
  34. 34.936 − 455 =
  35. 35.344 + 257 =
  36. 36.536 − 201 =
  37. 37.484 + 528 =
  38. 38.593 + 289 =
  39. 39.696 − 191 =
  40. 40.625 − 157 =

Answer key

  1. 124
  2. 819
  3. 1132
  4. 538
  5. 1122
  6. 105
  7. 750
  8. 957
  9. 1089
  10. 1143
  11. 304
  12. 274
  13. 321
  14. 412
  15. 226
  16. 553
  17. 952
  18. 227
  19. 190
  20. 324
  21. 202
  22. 698
  23. 294
  24. 1052
  25. 732
  26. 562
  27. 560
  28. 1268
  29. 448
  30. 458
  31. 887
  32. 111
  33. 133
  34. 481
  35. 601
  36. 335
  37. 1012
  38. 882
  39. 505
  40. 468

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