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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 772 · 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.?889 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 36 and take away the sum of its digits. What do you get?
  3. 3.258? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.72? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?239 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 21 and take away the sum of its digits. What do you get?
  7. 7.3?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.70? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 50 and take away the sum of its digits. What do you get?
  10. 10.161? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 20 and take away the sum of its digits. What do you get?
  12. 12.Take 85 and take away the sum of its digits. What do you get?
  13. 13.47? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 12 and take away the sum of its digits. What do you get?
  15. 15.?733 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.3?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 66 and take away the sum of its digits. What do you get?
  18. 18.620? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.381? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?530 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.73? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.302? 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.Take 33 and take away the sum of its digits. What do you get?
  25. 25.21?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.5?55 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.3?81 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 16 and take away the sum of its digits. What do you get?
  29. 29.1?45 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 68 and take away the sum of its digits. What do you get?
  31. 31.?68 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.2?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 32 and take away the sum of its digits. What do you get?
  34. 34.6?76 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 57 and take away the sum of its digits. What do you get?
  37. 37.38?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 52 and take away the sum of its digits. What do you get?
  39. 39.Take 24 and take away the sum of its digits. What do you get?
  40. 40.?956 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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