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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 116 · 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. 1.12?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.896? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.57?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.359? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.2?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.343? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 65 and take away the sum of its digits. What do you get?
  8. 8.Take 71 and take away the sum of its digits. What do you get?
  9. 9.39?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?490 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 89 and take away the sum of its digits. What do you get?
  12. 12.780? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 86 and take away the sum of its digits. What do you get?
  14. 14.9?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.52?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.7?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?809 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.550? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.11?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 68 and take away the sum of its digits. What do you get?
  22. 22.356? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.8?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 21 and take away the sum of its digits. What do you get?
  25. 25.Take 24 and take away the sum of its digits. What do you get?
  26. 26.1?16 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.1?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 23 and take away the sum of its digits. What do you get?
  29. 29.37?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.230? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.4?45 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?24 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.84?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.3?27 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.6?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.743? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.768? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 15 and take away the sum of its digits. What do you get?
  40. 40.?033 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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