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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 879 · 40 questions
TalentJR

The trick (Digits add to the 9 table): Add the digits you can see. Find the next number in the 9 table (9, 18, 27 …) above that total. The hidden digit is the difference. (Any number minus its digit sum is in the 9 table too.)

NameDateTime takenScore ___ / 40
  1. 1.Take 92 and take away the sum of its digits. What do you get?
  2. 2.Take 36 and take away the sum of its digits. What do you get?
  3. 3.207? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?970 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.56? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 50 and take away the sum of its digits. What do you get?
  7. 7.887? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.180? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.3?93 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.1?62 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 85 and take away the sum of its digits. What do you get?
  12. 12.Take 81 and take away the sum of its digits. What do you get?
  13. 13.?496 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 47 and take away the sum of its digits. What do you get?
  15. 15.17?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.351? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.65?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?111 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.230? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.67?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.13?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.1?17 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?362 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.3?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.810? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?146 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 93 and take away the sum of its digits. What do you get?
  28. 28.19?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.9?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.51?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 22 and take away the sum of its digits. What do you get?
  32. 32.Take 42 and take away the sum of its digits. What do you get?
  33. 33.?515 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?274 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.5?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 99 and take away the sum of its digits. What do you get?
  37. 37.Take 18 and take away the sum of its digits. What do you get?
  38. 38.15?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.5?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 53 and take away the sum of its digits. What do you get?

Answer key

  1. 81
  2. 27
  3. 9
  4. 2
  5. 7
  6. 45
  7. 4
  8. 9
  9. 3
  10. 9
  11. 72
  12. 72
  13. 8
  14. 36
  15. 6
  16. 9
  17. 7
  18. 6
  19. 4
  20. 9
  21. 8
  22. 9
  23. 7
  24. 8
  25. 9
  26. 7
  27. 81
  28. 8
  29. 9
  30. 7
  31. 18
  32. 36
  33. 7
  34. 5
  35. 3
  36. 81
  37. 9
  38. 3
  39. 2
  40. 45

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