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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 696 · 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 30 and take away the sum of its digits. What do you get?
  2. 2.Take 80 and take away the sum of its digits. What do you get?
  3. 3.4?22 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.609? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?415 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.5?89 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 55 and take away the sum of its digits. What do you get?
  8. 8.Take 68 and take away the sum of its digits. What do you get?
  9. 9.?088 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?836 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.19?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 32 and take away the sum of its digits. What do you get?
  13. 13.195? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.36?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?815 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?100 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.74?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?786 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 94 and take away the sum of its digits. What do you get?
  20. 20.65?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.121? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?561 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 59 and take away the sum of its digits. What do you get?
  24. 24.Take 60 and take away the sum of its digits. What do you get?
  25. 25.557? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?978 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 21 and take away the sum of its digits. What do you get?
  28. 28.?555 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.2?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.183? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?631 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?079 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 97 and take away the sum of its digits. What do you get?
  34. 34.Take 47 and take away the sum of its digits. What do you get?
  35. 35.8?85 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 64 and take away the sum of its digits. What do you get?
  37. 37.62?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.209? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 87 and take away the sum of its digits. What do you get?
  40. 40.81?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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