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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 341 · 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. 1.375 + 495 =
  2. 2.875 − 571 =
  3. 3.796 − 499 =
  4. 4.402 + 539 =
  5. 5.727 − 213 =
  6. 6.371 + 381 =
  7. 7.914 − 398 =
  8. 8.708 − 501 =
  9. 9.475 + 468 =
  10. 10.693 − 566 =
  11. 11.706 − 364 =
  12. 12.724 − 411 =
  13. 13.593 + 261 =
  14. 14.559 − 251 =
  15. 15.422 − 114 =
  16. 16.127 + 599 =
  17. 17.405 + 216 =
  18. 18.171 + 439 =
  19. 19.740 + 206 =
  20. 20.497 − 292 =
  21. 21.548 + 293 =
  22. 22.605 − 389 =
  23. 23.874 − 661 =
  24. 24.539 − 417 =
  25. 25.579 + 535 =
  26. 26.661 + 275 =
  27. 27.646 + 199 =
  28. 28.484 − 124 =
  29. 29.780 + 148 =
  30. 30.558 − 191 =
  31. 31.777 + 365 =
  32. 32.337 + 457 =
  33. 33.740 + 132 =
  34. 34.759 + 178 =
  35. 35.450 − 137 =
  36. 36.763 − 632 =
  37. 37.405 + 165 =
  38. 38.387 + 385 =
  39. 39.835 − 293 =
  40. 40.545 + 174 =

Answer key

  1. 870
  2. 304
  3. 297
  4. 941
  5. 514
  6. 752
  7. 516
  8. 207
  9. 943
  10. 127
  11. 342
  12. 313
  13. 854
  14. 308
  15. 308
  16. 726
  17. 621
  18. 610
  19. 946
  20. 205
  21. 841
  22. 216
  23. 213
  24. 122
  25. 1114
  26. 936
  27. 845
  28. 360
  29. 928
  30. 367
  31. 1142
  32. 794
  33. 872
  34. 937
  35. 313
  36. 131
  37. 570
  38. 772
  39. 542
  40. 719

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