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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 803 · 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. 1.14?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.28?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.683? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.8?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 71 and take away the sum of its digits. What do you get?
  6. 6.4?71 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.5?14 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.26?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 30 and take away the sum of its digits. What do you get?
  10. 10.Take 24 and take away the sum of its digits. What do you get?
  11. 11.Take 67 and take away the sum of its digits. What do you get?
  12. 12.6?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.740? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 52 and take away the sum of its digits. What do you get?
  15. 15.40?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.87?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.6?63 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.3?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.2?95 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.693? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 75 and take away the sum of its digits. What do you get?
  22. 22.?025 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 12 and take away the sum of its digits. What do you get?
  24. 24.7?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 18 and take away the sum of its digits. What do you get?
  26. 26.91? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 33 and take away the sum of its digits. What do you get?
  28. 28.Take 73 and take away the sum of its digits. What do you get?
  29. 29.45?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.605? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?941 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 97 and take away the sum of its digits. What do you get?
  33. 33.?338 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.3?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 40 and take away the sum of its digits. What do you get?
  36. 36.72?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.709? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 85 and take away the sum of its digits. What do you get?
  39. 39.71?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.79? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 4
  2. 3
  3. 1
  4. 6
  5. 63
  6. 6
  7. 8
  8. 3
  9. 27
  10. 18
  11. 54
  12. 5
  13. 7
  14. 45
  15. 2
  16. 1
  17. 3
  18. 2
  19. 2
  20. 9
  21. 63
  22. 2
  23. 9
  24. 8
  25. 9
  26. 8
  27. 27
  28. 63
  29. 7
  30. 7
  31. 4
  32. 81
  33. 4
  34. 2
  35. 36
  36. 9
  37. 2
  38. 72
  39. 9
  40. 2

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