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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 216 · 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 12 and take away the sum of its digits. What do you get?
  2. 2.Take 17 and take away the sum of its digits. What do you get?
  3. 3.?737 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 66 and take away the sum of its digits. What do you get?
  5. 5.?415 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 81 and take away the sum of its digits. What do you get?
  7. 7.?59 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.30?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.2?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 41 and take away the sum of its digits. What do you get?
  11. 11.320? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.92? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 67 and take away the sum of its digits. What do you get?
  14. 14.Take 26 and take away the sum of its digits. What do you get?
  15. 15.Take 32 and take away the sum of its digits. What do you get?
  16. 16.8?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.61? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 55 and take away the sum of its digits. What do you get?
  19. 19.?986 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 82 and take away the sum of its digits. What do you get?
  21. 21.35?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 30 and take away the sum of its digits. What do you get?
  23. 23.2?63 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?119 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.213? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?826 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 62 and take away the sum of its digits. What do you get?
  28. 28.1?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.83?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.55?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 18 and take away the sum of its digits. What do you get?
  32. 32.?457 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.7?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 75 and take away the sum of its digits. What do you get?
  35. 35.?709 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 20 and take away the sum of its digits. What do you get?
  37. 37.Take 94 and take away the sum of its digits. What do you get?
  38. 38.?204 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 33 and take away the sum of its digits. What do you get?
  40. 40.?358 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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