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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 10 · 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.?597 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.79?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?750 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.91? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?197 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.36?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.515? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 31 and take away the sum of its digits. What do you get?
  9. 9.6?28 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 36 and take away the sum of its digits. What do you get?
  11. 11.?715 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 95 and take away the sum of its digits. What do you get?
  13. 13.100? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?010 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 39 and take away the sum of its digits. What do you get?
  16. 16.?555 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.346? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 59 and take away the sum of its digits. What do you get?
  19. 19.Take 66 and take away the sum of its digits. What do you get?
  20. 20.2?57 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.88? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?301 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 47 and take away the sum of its digits. What do you get?
  24. 24.Take 93 and take away the sum of its digits. What do you get?
  25. 25.Take 61 and take away the sum of its digits. What do you get?
  26. 26.Take 80 and take away the sum of its digits. What do you get?
  27. 27.194? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?502 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.1?54 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.5?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?94 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 74 and take away the sum of its digits. What do you get?
  33. 33.4?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 78 and take away the sum of its digits. What do you get?
  35. 35.Take 46 and take away the sum of its digits. What do you get?
  36. 36.Take 70 and take away the sum of its digits. What do you get?
  37. 37.83? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?245 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 34 and take away the sum of its digits. What do you get?
  40. 40.Take 63 and take away the sum of its digits. What do you get?

Answer key

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

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