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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 766 · 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. 1.650? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 22 and take away the sum of its digits. What do you get?
  3. 3.5?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 58 and take away the sum of its digits. What do you get?
  5. 5.7?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 12 and take away the sum of its digits. What do you get?
  7. 7.1?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?870 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?472 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.105? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.7?43 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 97 and take away the sum of its digits. What do you get?
  13. 13.Take 45 and take away the sum of its digits. What do you get?
  14. 14.7?67 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.1?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 86 and take away the sum of its digits. What do you get?
  17. 17.Take 17 and take away the sum of its digits. What do you get?
  18. 18.Take 46 and take away the sum of its digits. What do you get?
  19. 19.24?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.789? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?021 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 75 and take away the sum of its digits. What do you get?
  23. 23.?097 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?636 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 27 and take away the sum of its digits. What do you get?
  26. 26.Take 73 and take away the sum of its digits. What do you get?
  27. 27.?59 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.12?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.74? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.83? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.600? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.61?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.1?33 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?205 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.1?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 99 and take away the sum of its digits. What do you get?
  37. 37.Take 51 and take away the sum of its digits. What do you get?
  38. 38.2?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 93 and take away the sum of its digits. What do you get?
  40. 40.?560 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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