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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 727 · 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. 1.1?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.137? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 28 and take away the sum of its digits. What do you get?
  4. 4.?118 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?660 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.5?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 68 and take away the sum of its digits. What do you get?
  8. 8.?751 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 70 and take away the sum of its digits. What do you get?
  10. 10.Take 45 and take away the sum of its digits. What do you get?
  11. 11.?419 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.6?36 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.18?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.30?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 20 and take away the sum of its digits. What do you get?
  16. 16.Take 24 and take away the sum of its digits. What do you get?
  17. 17.?728 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.37?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.1?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.109? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?71 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?139 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.7?29 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.230? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?093 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.6?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?262 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 48 and take away the sum of its digits. What do you get?
  29. 29.1?58 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.789? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?029 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?622 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.135? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 16 and take away the sum of its digits. What do you get?
  35. 35.Take 37 and take away the sum of its digits. What do you get?
  36. 36.?034 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.8?69 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 72 and take away the sum of its digits. What do you get?
  39. 39.?626 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?769 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. 7
  3. 18
  4. 8
  5. 6
  6. 1
  7. 54
  8. 5
  9. 63
  10. 36
  11. 4
  12. 3
  13. 2
  14. 6
  15. 18
  16. 18
  17. 1
  18. 8
  19. 5
  20. 8
  21. 1
  22. 5
  23. 9
  24. 4
  25. 6
  26. 2
  27. 8
  28. 36
  29. 4
  30. 3
  31. 7
  32. 8
  33. 9
  34. 9
  35. 27
  36. 2
  37. 4
  38. 63
  39. 4
  40. 5

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