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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 410 · 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. 1.842? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?649 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.62?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.5?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.550? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?541 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?210 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?557 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.3?28 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 12 and take away the sum of its digits. What do you get?
  11. 11.?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 40 and take away the sum of its digits. What do you get?
  13. 13.38?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.70?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.8?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.306? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.101? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.5?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.64?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?867 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.83?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.6?61 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.1?01 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.533? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?174 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.7?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.77?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.54?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?519 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.739? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.5?75 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.4?28 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 95 and take away the sum of its digits. What do you get?
  34. 34.69?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?385 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.257? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 15 and take away the sum of its digits. What do you get?
  38. 38.59?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?322 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 20 and take away the sum of its digits. What do you get?

Answer key

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

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