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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 830 · 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. 1.716? 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.Take 80 and take away the sum of its digits. What do you get?
  4. 4.5?86 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?251 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.82?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.24?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 92 and take away the sum of its digits. What do you get?
  9. 9.6?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?244 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 76 and take away the sum of its digits. What do you get?
  12. 12.785? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.55?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 35 and take away the sum of its digits. What do you get?
  15. 15.Take 13 and take away the sum of its digits. What do you get?
  16. 16.Take 47 and take away the sum of its digits. What do you get?
  17. 17.704? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?035 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 18 and take away the sum of its digits. What do you get?
  20. 20.1?17 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 32 and take away the sum of its digits. What do you get?
  22. 22.Take 14 and take away the sum of its digits. What do you get?
  23. 23.Take 59 and take away the sum of its digits. What do you get?
  24. 24.738? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 29 and take away the sum of its digits. What do you get?
  26. 26.41? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 56 and take away the sum of its digits. What do you get?
  28. 28.523? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 72 and take away the sum of its digits. What do you get?
  30. 30.Take 65 and take away the sum of its digits. What do you get?
  31. 31.5?67 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 70 and take away the sum of its digits. What do you get?
  33. 33.7?53 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?976 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?291 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.93? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?27 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 74 and take away the sum of its digits. What do you get?
  39. 39.Take 91 and take away the sum of its digits. What do you get?
  40. 40.29?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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