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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 483 · 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 72 and take away the sum of its digits. What do you get?
  2. 2.?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 87 and take away the sum of its digits. What do you get?
  4. 4.6?81 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 79 and take away the sum of its digits. What do you get?
  6. 6.42?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 54 and take away the sum of its digits. What do you get?
  8. 8.85?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 88 and take away the sum of its digits. What do you get?
  10. 10.3?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.2?36 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.241? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.1?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.337? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 62 and take away the sum of its digits. What do you get?
  16. 16.?707 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.885? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?079 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.81?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.8?17 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 36 and take away the sum of its digits. What do you get?
  22. 22.?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.506? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 74 and take away the sum of its digits. What do you get?
  25. 25.?775 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 46 and take away the sum of its digits. What do you get?
  27. 27.117? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.7?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 37 and take away the sum of its digits. What do you get?
  30. 30.Take 56 and take away the sum of its digits. What do you get?
  31. 31.3?59 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?636 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 47 and take away the sum of its digits. What do you get?
  34. 34.579? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 19 and take away the sum of its digits. What do you get?
  36. 36.4?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?367 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 69 and take away the sum of its digits. What do you get?
  40. 40.716? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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