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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 663 · 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 15 and take away the sum of its digits. What do you get?
  2. 2.?578 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?064 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.3?32 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 30 and take away the sum of its digits. What do you get?
  6. 6.741? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.43?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 72 and take away the sum of its digits. What do you get?
  9. 9.7?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.686? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.3?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 31 and take away the sum of its digits. What do you get?
  13. 13.Take 98 and take away the sum of its digits. What do you get?
  14. 14.761? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?866 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 61 and take away the sum of its digits. What do you get?
  17. 17.Take 99 and take away the sum of its digits. What do you get?
  18. 18.3?26 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 77 and take away the sum of its digits. What do you get?
  20. 20.44?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.387? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?146 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 76 and take away the sum of its digits. What do you get?
  24. 24.?107 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?296 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.3?63 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?454 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?259 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 91 and take away the sum of its digits. What do you get?
  30. 30.Take 70 and take away the sum of its digits. What do you get?
  31. 31.1?37 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 18 and take away the sum of its digits. What do you get?
  33. 33.5?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.181? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 93 and take away the sum of its digits. What do you get?
  36. 36.43?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?030 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?760 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.10?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.839? 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. 7
  3. 8
  4. 1
  5. 27
  6. 6
  7. 2
  8. 63
  9. 5
  10. 7
  11. 2
  12. 27
  13. 81
  14. 4
  15. 7
  16. 54
  17. 81
  18. 7
  19. 63
  20. 1
  21. 9
  22. 7
  23. 63
  24. 1
  25. 1
  26. 6
  27. 5
  28. 2
  29. 81
  30. 63
  31. 7
  32. 9
  33. 6
  34. 8
  35. 81
  36. 1
  37. 6
  38. 5
  39. 9
  40. 7

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