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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 507 · 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 19 and take away the sum of its digits. What do you get?
  2. 2.?210 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?103 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 59 and take away the sum of its digits. What do you get?
  5. 5.Take 50 and take away the sum of its digits. What do you get?
  6. 6.Take 60 and take away the sum of its digits. What do you get?
  7. 7.826? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 85 and take away the sum of its digits. What do you get?
  9. 9.8?16 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?740 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.240? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.6?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.6?52 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?570 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.809? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.38?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 58 and take away the sum of its digits. What do you get?
  18. 18.?911 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?236 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.175? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.825? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.30?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 55 and take away the sum of its digits. What do you get?
  24. 24.Take 17 and take away the sum of its digits. What do you get?
  25. 25.Take 91 and take away the sum of its digits. What do you get?
  26. 26.686? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 66 and take away the sum of its digits. What do you get?
  28. 28.Take 37 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. 30.78? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.680? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 22 and take away the sum of its digits. What do you get?
  33. 33.?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.2?57 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.5?07 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?593 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.361? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.6?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.50?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 52 and take away the sum of its digits. What do you get?

Answer key

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

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