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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 314 · 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.?417 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 23 and take away the sum of its digits. What do you get?
  3. 3.76?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?328 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 98 and take away the sum of its digits. What do you get?
  6. 6.Take 62 and take away the sum of its digits. What do you get?
  7. 7.?566 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?867 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?935 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.15?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 30 and take away the sum of its digits. What do you get?
  12. 12.128? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 81 and take away the sum of its digits. What do you get?
  14. 14.5?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.6?62 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 24 and take away the sum of its digits. What do you get?
  17. 17.629? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?239 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.805? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 28 and take away the sum of its digits. What do you get?
  21. 21.Take 83 and take away the sum of its digits. What do you get?
  22. 22.?168 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 37 and take away the sum of its digits. What do you get?
  24. 24.7?64 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.1?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.205? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.63? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.4?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?23 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.3?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?740 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.214? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.14?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.5?59 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.18?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 14 and take away the sum of its digits. What do you get?
  37. 37.316? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 17 and take away the sum of its digits. What do you get?
  39. 39.47?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.789? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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