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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 258 · 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. 1.724 − 585 =
  2. 2.948 − 432 =
  3. 3.412 − 146 =
  4. 4.762 + 617 =
  5. 5.603 + 124 =
  6. 6.721 − 397 =
  7. 7.350 + 519 =
  8. 8.378 + 193 =
  9. 9.582 + 205 =
  10. 10.484 − 384 =
  11. 11.546 − 401 =
  12. 12.518 + 282 =
  13. 13.910 − 213 =
  14. 14.875 − 314 =
  15. 15.549 − 172 =
  16. 16.723 − 385 =
  17. 17.294 + 411 =
  18. 18.561 − 295 =
  19. 19.186 + 278 =
  20. 20.199 + 117 =
  21. 21.735 + 459 =
  22. 22.361 + 529 =
  23. 23.132 + 442 =
  24. 24.508 + 181 =
  25. 25.907 − 276 =
  26. 26.881 − 767 =
  27. 27.412 − 181 =
  28. 28.697 − 147 =
  29. 29.550 − 194 =
  30. 30.541 + 132 =
  31. 31.549 − 139 =
  32. 32.516 − 193 =
  33. 33.655 + 304 =
  34. 34.144 + 611 =
  35. 35.904 − 297 =
  36. 36.501 + 271 =
  37. 37.636 − 195 =
  38. 38.924 − 586 =
  39. 39.970 − 695 =
  40. 40.475 − 198 =

Answer key

  1. 139
  2. 516
  3. 266
  4. 1379
  5. 727
  6. 324
  7. 869
  8. 571
  9. 787
  10. 100
  11. 145
  12. 800
  13. 697
  14. 561
  15. 377
  16. 338
  17. 705
  18. 266
  19. 464
  20. 316
  21. 1194
  22. 890
  23. 574
  24. 689
  25. 631
  26. 114
  27. 231
  28. 550
  29. 356
  30. 673
  31. 410
  32. 323
  33. 959
  34. 755
  35. 607
  36. 772
  37. 441
  38. 338
  39. 275
  40. 277

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