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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 87 · 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. 1.8?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?331 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 99 and take away the sum of its digits. What do you get?
  4. 4.Take 39 and take away the sum of its digits. What do you get?
  5. 5.?656 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 22 and take away the sum of its digits. What do you get?
  7. 7.85?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 87 and take away the sum of its digits. What do you get?
  9. 9.?507 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.97? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.11?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.6?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?688 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 33 and take away the sum of its digits. What do you get?
  15. 15.52?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?390 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 48 and take away the sum of its digits. What do you get?
  18. 18.Take 59 and take away the sum of its digits. What do you get?
  19. 19.Take 58 and take away the sum of its digits. What do you get?
  20. 20.Take 85 and take away the sum of its digits. What do you get?
  21. 21.Take 25 and take away the sum of its digits. What do you get?
  22. 22.260? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?562 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.205? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?362 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.8?91 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.37?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 60 and take away the sum of its digits. What do you get?
  30. 30.?966 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?922 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?203 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?437 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.17?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 37 and take away the sum of its digits. What do you get?
  36. 36.856? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 94 and take away the sum of its digits. What do you get?
  38. 38.Take 97 and take away the sum of its digits. What do you get?
  39. 39.698? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.5?92 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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