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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 436 · 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. 1.529 − 415 =
  2. 2.765 + 452 =
  3. 3.956 − 247 =
  4. 4.516 − 206 =
  5. 5.928 − 351 =
  6. 6.637 − 439 =
  7. 7.399 + 213 =
  8. 8.713 + 135 =
  9. 9.732 + 688 =
  10. 10.778 + 674 =
  11. 11.794 − 524 =
  12. 12.777 + 589 =
  13. 13.306 + 606 =
  14. 14.724 − 198 =
  15. 15.595 + 182 =
  16. 16.571 + 364 =
  17. 17.926 − 511 =
  18. 18.493 + 498 =
  19. 19.177 + 379 =
  20. 20.585 + 573 =
  21. 21.242 + 471 =
  22. 22.428 + 529 =
  23. 23.736 − 232 =
  24. 24.262 + 192 =
  25. 25.466 + 232 =
  26. 26.132 + 495 =
  27. 27.591 + 244 =
  28. 28.974 − 451 =
  29. 29.896 − 289 =
  30. 30.664 + 175 =
  31. 31.160 + 592 =
  32. 32.700 + 634 =
  33. 33.518 + 456 =
  34. 34.286 + 601 =
  35. 35.784 + 311 =
  36. 36.164 + 416 =
  37. 37.182 + 363 =
  38. 38.386 + 579 =
  39. 39.855 − 134 =
  40. 40.171 + 537 =

Answer key

  1. 114
  2. 1217
  3. 709
  4. 310
  5. 577
  6. 198
  7. 612
  8. 848
  9. 1420
  10. 1452
  11. 270
  12. 1366
  13. 912
  14. 526
  15. 777
  16. 935
  17. 415
  18. 991
  19. 556
  20. 1158
  21. 713
  22. 957
  23. 504
  24. 454
  25. 698
  26. 627
  27. 835
  28. 523
  29. 607
  30. 839
  31. 752
  32. 1334
  33. 974
  34. 887
  35. 1095
  36. 580
  37. 545
  38. 965
  39. 721
  40. 708

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