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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 684 · 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.?728 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 20 and take away the sum of its digits. What do you get?
  3. 3.?692 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?140 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 75 and take away the sum of its digits. What do you get?
  6. 6.?707 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 87 and take away the sum of its digits. What do you get?
  8. 8.?464 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.54?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.516? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 72 and take away the sum of its digits. What do you get?
  12. 12.1?91 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.64? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.144? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.5?29 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.755? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 31 and take away the sum of its digits. What do you get?
  18. 18.?784 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.85?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 70 and take away the sum of its digits. What do you get?
  21. 21.Take 27 and take away the sum of its digits. What do you get?
  22. 22.?393 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?980 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 23 and take away the sum of its digits. What do you get?
  25. 25.55?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?021 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.772? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.8?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?716 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.484? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.87?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.4?85 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 79 and take away the sum of its digits. What do you get?
  34. 34.3?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.6?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?014 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.609? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 82 and take away the sum of its digits. What do you get?
  40. 40.Take 32 and take away the sum of its digits. What do you get?

Answer key

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

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