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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 402 · 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. 1.520? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.2?74 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 17 and take away the sum of its digits. What do you get?
  4. 4.Take 52 and take away the sum of its digits. What do you get?
  5. 5.?57 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 98 and take away the sum of its digits. What do you get?
  7. 7.Take 45 and take away the sum of its digits. What do you get?
  8. 8.5?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.49?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.8?89 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 37 and take away the sum of its digits. What do you get?
  12. 12.25?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 70 and take away the sum of its digits. What do you get?
  14. 14.8?78 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.38?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 94 and take away the sum of its digits. What do you get?
  17. 17.2?92 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.361? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.6?57 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?764 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 49 and take away the sum of its digits. What do you get?
  22. 22.Take 89 and take away the sum of its digits. What do you get?
  23. 23.?575 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.500? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 44 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. 27.2?91 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 29 and take away the sum of its digits. What do you get?
  29. 29.Take 91 and take away the sum of its digits. What do you get?
  30. 30.Take 99 and take away the sum of its digits. What do you get?
  31. 31.?457 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.138? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.8?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 85 and take away the sum of its digits. What do you get?
  35. 35.Take 77 and take away the sum of its digits. What do you get?
  36. 36.45?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 12 and take away the sum of its digits. What do you get?
  38. 38.?233 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.641? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 71 and take away the sum of its digits. What do you get?

Answer key

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

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