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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 806 · 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 13 and take away the sum of its digits. What do you get?
  2. 2.Take 35 and take away the sum of its digits. What do you get?
  3. 3.?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.64?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 41 and take away the sum of its digits. What do you get?
  6. 6.71? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 83 and take away the sum of its digits. What do you get?
  8. 8.?533 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?420 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?042 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 68 and take away the sum of its digits. What do you get?
  12. 12.?472 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.680? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?710 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 50 and take away the sum of its digits. What do you get?
  16. 16.870? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.439? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.815? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 54 and take away the sum of its digits. What do you get?
  20. 20.Take 71 and take away the sum of its digits. What do you get?
  21. 21.329? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.402? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 94 and take away the sum of its digits. What do you get?
  24. 24.5?54 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.8?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 18 and take away the sum of its digits. What do you get?
  28. 28.Take 96 and take away the sum of its digits. What do you get?
  29. 29.320? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 28 and take away the sum of its digits. What do you get?
  31. 31.71?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?943 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.25?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.432? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.5?52 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.64?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?700 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 29 and take away the sum of its digits. What do you get?
  39. 39.Take 38 and take away the sum of its digits. What do you get?
  40. 40.214? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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