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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 339 · 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.?931 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?205 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 54 and take away the sum of its digits. What do you get?
  4. 4.?848 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 60 and take away the sum of its digits. What do you get?
  6. 6.10?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 94 and take away the sum of its digits. What do you get?
  8. 8.?968 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.8?61 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.55?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 33 and take away the sum of its digits. What do you get?
  13. 13.?724 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 25 and take away the sum of its digits. What do you get?
  15. 15.Take 52 and take away the sum of its digits. What do you get?
  16. 16.27?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 24 and take away the sum of its digits. What do you get?
  18. 18.Take 89 and take away the sum of its digits. What do you get?
  19. 19.26?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 56 and take away the sum of its digits. What do you get?
  21. 21.426? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.522? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 23 and take away the sum of its digits. What do you get?
  24. 24.541? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?994 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?008 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.53?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 90 and take away the sum of its digits. What do you get?
  29. 29.Take 49 and take away the sum of its digits. What do you get?
  30. 30.31?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.544? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.45?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.5?36 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?850 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 21 and take away the sum of its digits. What do you get?
  36. 36.Take 37 and take away the sum of its digits. What do you get?
  37. 37.Take 48 and take away the sum of its digits. What do you get?
  38. 38.496? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?943 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 87 and take away the sum of its digits. What do you get?

Answer key

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

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