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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 796 · 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. 1.132 + 425 =
  2. 2.690 − 331 =
  3. 3.204 + 639 =
  4. 4.695 + 608 =
  5. 5.426 + 646 =
  6. 6.603 − 352 =
  7. 7.554 − 209 =
  8. 8.339 + 119 =
  9. 9.432 − 146 =
  10. 10.544 − 235 =
  11. 11.126 + 578 =
  12. 12.854 − 711 =
  13. 13.593 − 114 =
  14. 14.463 + 281 =
  15. 15.611 + 609 =
  16. 16.711 + 446 =
  17. 17.742 − 357 =
  18. 18.939 − 369 =
  19. 19.685 + 115 =
  20. 20.651 + 574 =
  21. 21.458 − 219 =
  22. 22.720 + 387 =
  23. 23.893 − 581 =
  24. 24.908 − 115 =
  25. 25.388 + 619 =
  26. 26.409 + 496 =
  27. 27.870 − 507 =
  28. 28.897 − 342 =
  29. 29.674 + 407 =
  30. 30.776 − 568 =
  31. 31.617 + 163 =
  32. 32.470 + 161 =
  33. 33.670 + 171 =
  34. 34.284 + 454 =
  35. 35.706 − 212 =
  36. 36.909 − 679 =
  37. 37.701 − 521 =
  38. 38.617 + 472 =
  39. 39.666 + 186 =
  40. 40.788 + 451 =

Answer key

  1. 557
  2. 359
  3. 843
  4. 1303
  5. 1072
  6. 251
  7. 345
  8. 458
  9. 286
  10. 309
  11. 704
  12. 143
  13. 479
  14. 744
  15. 1220
  16. 1157
  17. 385
  18. 570
  19. 800
  20. 1225
  21. 239
  22. 1107
  23. 312
  24. 793
  25. 1007
  26. 905
  27. 363
  28. 555
  29. 1081
  30. 208
  31. 780
  32. 631
  33. 841
  34. 738
  35. 494
  36. 230
  37. 180
  38. 1089
  39. 852
  40. 1239

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