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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 159 · 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. 1.3?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 94 and take away the sum of its digits. What do you get?
  3. 3.720? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.567? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.96? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?196 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.50?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?190 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?692 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.477? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.29?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?250 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.49? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.131? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 76 and take away the sum of its digits. What do you get?
  17. 17.?726 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.29? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.297? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.344? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?170 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.461? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 27 and take away the sum of its digits. What do you get?
  24. 24.75? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 78 and take away the sum of its digits. What do you get?
  26. 26.Take 32 and take away the sum of its digits. What do you get?
  27. 27.Take 13 and take away the sum of its digits. What do you get?
  28. 28.795? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?470 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 31 and take away the sum of its digits. What do you get?
  31. 31.43? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.6?14 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.322? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 53 and take away the sum of its digits. What do you get?
  35. 35.345? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.62?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.57?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?961 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.41?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?485 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 2
  2. 81
  3. 9
  4. 9
  5. 3
  6. 2
  7. 1
  8. 8
  9. 5
  10. 1
  11. 9
  12. 1
  13. 2
  14. 5
  15. 4
  16. 63
  17. 3
  18. 7
  19. 9
  20. 7
  21. 1
  22. 7
  23. 18
  24. 6
  25. 63
  26. 27
  27. 9
  28. 6
  29. 7
  30. 27
  31. 2
  32. 7
  33. 2
  34. 45
  35. 6
  36. 5
  37. 6
  38. 2
  39. 1
  40. 1

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