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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 765 · 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. 1.77?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.12?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?249 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 85 and take away the sum of its digits. What do you get?
  5. 5.?893 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 88 and take away the sum of its digits. What do you get?
  7. 7.781? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.582? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.517? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.79?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 18 and take away the sum of its digits. What do you get?
  12. 12.68?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 27 and take away the sum of its digits. What do you get?
  14. 14.Take 60 and take away the sum of its digits. What do you get?
  15. 15.80?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 12 and take away the sum of its digits. What do you get?
  17. 17.89?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?76 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.3?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.3?32 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.6?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 54 and take away the sum of its digits. What do you get?
  23. 23.9?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?185 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.6?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.595? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 30 and take away the sum of its digits. What do you get?
  28. 28.?48 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 67 and take away the sum of its digits. What do you get?
  30. 30.35? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.8?88 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 93 and take away the sum of its digits. What do you get?
  33. 33.?392 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?142 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 89 and take away the sum of its digits. What do you get?
  36. 36.?454 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?214 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 79 and take away the sum of its digits. What do you get?
  39. 39.Take 97 and take away the sum of its digits. What do you get?
  40. 40.36?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 3
  2. 7
  3. 3
  4. 72
  5. 7
  6. 72
  7. 2
  8. 3
  9. 5
  10. 8
  11. 9
  12. 4
  13. 18
  14. 54
  15. 1
  16. 9
  17. 9
  18. 5
  19. 2
  20. 1
  21. 4
  22. 45
  23. 4
  24. 4
  25. 5
  26. 8
  27. 27
  28. 6
  29. 54
  30. 1
  31. 3
  32. 81
  33. 4
  34. 2
  35. 72
  36. 5
  37. 2
  38. 63
  39. 81
  40. 9

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