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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 39 · 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 36 and take away the sum of its digits. What do you get?
  2. 2.?230 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.690? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 81 and take away the sum of its digits. What do you get?
  5. 5.25? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.53?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.880? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 76 and take away the sum of its digits. What do you get?
  9. 9.Take 31 and take away the sum of its digits. What do you get?
  10. 10.59?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.422? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.2?28 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 21 and take away the sum of its digits. What do you get?
  14. 14.Take 85 and take away the sum of its digits. What do you get?
  15. 15.Take 95 and take away the sum of its digits. What do you get?
  16. 16.815? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 38 and take away the sum of its digits. What do you get?
  18. 18.Take 57 and take away the sum of its digits. What do you get?
  19. 19.17?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 65 and take away the sum of its digits. What do you get?
  21. 21.Take 14 and take away the sum of its digits. What do you get?
  22. 22.64? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.57?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.4?83 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.105? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?769 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?062 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.66?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?956 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 19 and take away the sum of its digits. What do you get?
  31. 31.Take 74 and take away the sum of its digits. What do you get?
  32. 32.62?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 59 and take away the sum of its digits. What do you get?
  34. 34.660? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.509? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?017 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 26 and take away the sum of its digits. What do you get?
  38. 38.7?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.59?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.69?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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