← 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 833 · 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. 1.551 − 432 =
  2. 2.629 + 536 =
  3. 3.430 − 205 =
  4. 4.618 + 211 =
  5. 5.544 + 236 =
  6. 6.715 − 164 =
  7. 7.415 − 137 =
  8. 8.148 + 151 =
  9. 9.218 + 604 =
  10. 10.570 + 241 =
  11. 11.279 + 244 =
  12. 12.435 + 118 =
  13. 13.501 − 269 =
  14. 14.940 − 672 =
  15. 15.497 − 346 =
  16. 16.355 + 669 =
  17. 17.210 + 503 =
  18. 18.535 + 491 =
  19. 19.263 + 673 =
  20. 20.130 + 586 =
  21. 21.536 + 346 =
  22. 22.760 + 632 =
  23. 23.496 + 299 =
  24. 24.270 + 424 =
  25. 25.460 − 297 =
  26. 26.239 + 447 =
  27. 27.688 − 405 =
  28. 28.156 + 567 =
  29. 29.790 − 112 =
  30. 30.652 + 659 =
  31. 31.384 + 577 =
  32. 32.939 − 448 =
  33. 33.720 − 176 =
  34. 34.449 + 198 =
  35. 35.277 + 199 =
  36. 36.141 + 233 =
  37. 37.688 − 433 =
  38. 38.525 + 374 =
  39. 39.428 + 369 =
  40. 40.356 + 393 =

Answer key

  1. 119
  2. 1165
  3. 225
  4. 829
  5. 780
  6. 551
  7. 278
  8. 299
  9. 822
  10. 811
  11. 523
  12. 553
  13. 232
  14. 268
  15. 151
  16. 1024
  17. 713
  18. 1026
  19. 936
  20. 716
  21. 882
  22. 1392
  23. 795
  24. 694
  25. 163
  26. 686
  27. 283
  28. 723
  29. 678
  30. 1311
  31. 961
  32. 491
  33. 544
  34. 647
  35. 476
  36. 374
  37. 255
  38. 899
  39. 797
  40. 749

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