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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 926 · 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. 1.506 + 311 =
  2. 2.722 + 306 =
  3. 3.694 − 443 =
  4. 4.344 + 351 =
  5. 5.183 + 267 =
  6. 6.361 + 116 =
  7. 7.378 + 604 =
  8. 8.623 − 167 =
  9. 9.928 − 214 =
  10. 10.513 + 368 =
  11. 11.196 + 594 =
  12. 12.434 − 308 =
  13. 13.758 − 589 =
  14. 14.690 + 622 =
  15. 15.725 + 327 =
  16. 16.212 + 383 =
  17. 17.515 + 422 =
  18. 18.314 + 352 =
  19. 19.451 − 211 =
  20. 20.965 − 573 =
  21. 21.417 − 225 =
  22. 22.580 − 473 =
  23. 23.387 + 335 =
  24. 24.218 + 193 =
  25. 25.690 + 245 =
  26. 26.772 + 609 =
  27. 27.569 − 208 =
  28. 28.216 + 597 =
  29. 29.970 − 312 =
  30. 30.347 + 272 =
  31. 31.903 − 218 =
  32. 32.495 + 136 =
  33. 33.395 + 679 =
  34. 34.448 − 333 =
  35. 35.773 − 123 =
  36. 36.420 + 243 =
  37. 37.939 − 281 =
  38. 38.132 + 144 =
  39. 39.515 − 288 =
  40. 40.776 + 623 =

Answer key

  1. 817
  2. 1028
  3. 251
  4. 695
  5. 450
  6. 477
  7. 982
  8. 456
  9. 714
  10. 881
  11. 790
  12. 126
  13. 169
  14. 1312
  15. 1052
  16. 595
  17. 937
  18. 666
  19. 240
  20. 392
  21. 192
  22. 107
  23. 722
  24. 411
  25. 935
  26. 1381
  27. 361
  28. 813
  29. 658
  30. 619
  31. 685
  32. 631
  33. 1074
  34. 115
  35. 650
  36. 663
  37. 658
  38. 276
  39. 227
  40. 1399

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