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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 953 · 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. 1.487 + 327 =
  2. 2.657 − 468 =
  3. 3.377 + 597 =
  4. 4.127 + 573 =
  5. 5.478 − 184 =
  6. 6.433 + 512 =
  7. 7.156 + 672 =
  8. 8.467 − 223 =
  9. 9.706 − 556 =
  10. 10.600 + 221 =
  11. 11.922 − 291 =
  12. 12.850 − 325 =
  13. 13.154 + 671 =
  14. 14.939 − 657 =
  15. 15.401 + 315 =
  16. 16.259 + 511 =
  17. 17.704 − 548 =
  18. 18.796 − 514 =
  19. 19.549 − 429 =
  20. 20.517 + 219 =
  21. 21.605 − 137 =
  22. 22.726 − 247 =
  23. 23.557 + 644 =
  24. 24.572 − 417 =
  25. 25.650 + 481 =
  26. 26.528 − 332 =
  27. 27.811 − 159 =
  28. 28.169 + 336 =
  29. 29.273 + 207 =
  30. 30.560 + 436 =
  31. 31.283 + 113 =
  32. 32.570 − 235 =
  33. 33.482 + 277 =
  34. 34.302 + 188 =
  35. 35.297 + 266 =
  36. 36.704 + 432 =
  37. 37.476 + 132 =
  38. 38.941 − 795 =
  39. 39.630 − 444 =
  40. 40.815 − 121 =

Answer key

  1. 814
  2. 189
  3. 974
  4. 700
  5. 294
  6. 945
  7. 828
  8. 244
  9. 150
  10. 821
  11. 631
  12. 525
  13. 825
  14. 282
  15. 716
  16. 770
  17. 156
  18. 282
  19. 120
  20. 736
  21. 468
  22. 479
  23. 1201
  24. 155
  25. 1131
  26. 196
  27. 652
  28. 505
  29. 480
  30. 996
  31. 396
  32. 335
  33. 759
  34. 490
  35. 563
  36. 1136
  37. 608
  38. 146
  39. 186
  40. 694

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