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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 920 · 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.?516 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.126? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 14 and take away the sum of its digits. What do you get?
  4. 4.30?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 81 and take away the sum of its digits. What do you get?
  6. 6.?753 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.1?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.3?95 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?901 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.8?26 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?859 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 18 and take away the sum of its digits. What do you get?
  13. 13.?974 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 91 and take away the sum of its digits. What do you get?
  15. 15.5?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.6?57 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.8?93 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.6?24 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.735? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 31 and take away the sum of its digits. What do you get?
  22. 22.14?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 15 and take away the sum of its digits. What do you get?
  24. 24.?88 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.75?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?674 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 90 and take away the sum of its digits. What do you get?
  28. 28.?339 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 47 and take away the sum of its digits. What do you get?
  30. 30.Take 39 and take away the sum of its digits. What do you get?
  31. 31.Take 22 and take away the sum of its digits. What do you get?
  32. 32.8?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?065 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.6?53 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 49 and take away the sum of its digits. What do you get?
  36. 36.5?64 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 93 and take away the sum of its digits. What do you get?
  38. 38.?091 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 16 and take away the sum of its digits. What do you get?
  40. 40.81?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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