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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 669 · 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 27 and take away the sum of its digits. What do you get?
  2. 2.72?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?345 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.228? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.320? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?028 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.65?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?098 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 98 and take away the sum of its digits. What do you get?
  10. 10.Take 82 and take away the sum of its digits. What do you get?
  11. 11.16?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.50?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?001 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 13 and take away the sum of its digits. What do you get?
  15. 15.Take 53 and take away the sum of its digits. What do you get?
  16. 16.Take 17 and take away the sum of its digits. What do you get?
  17. 17.82?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.2?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.8?71 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.3?45 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 15 and take away the sum of its digits. What do you get?
  22. 22.2?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 50 and take away the sum of its digits. What do you get?
  24. 24.2?81 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?042 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 24 and take away the sum of its digits. What do you get?
  27. 27.Take 91 and take away the sum of its digits. What do you get?
  28. 28.Take 49 and take away the sum of its digits. What do you get?
  29. 29.Take 18 and take away the sum of its digits. What do you get?
  30. 30.230? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?034 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.5?45 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 59 and take away the sum of its digits. What do you get?
  35. 35.Take 56 and take away the sum of its digits. What do you get?
  36. 36.402? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.648? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?003 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.422? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 89 and take away the sum of its digits. What do you get?

Answer key

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

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