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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 458 · 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. 1.409? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?61 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?177 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 86 and take away the sum of its digits. What do you get?
  5. 5.Take 60 and take away the sum of its digits. What do you get?
  6. 6.?515 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 53 and take away the sum of its digits. What do you get?
  8. 8.1?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.74?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.48?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.1?15 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.83?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.4?61 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.54?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.69?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 23 and take away the sum of its digits. What do you get?
  17. 17.60? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.3?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 20 and take away the sum of its digits. What do you get?
  20. 20.686? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?092 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 35 and take away the sum of its digits. What do you get?
  23. 23.Take 34 and take away the sum of its digits. What do you get?
  24. 24.20?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?120 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 67 and take away the sum of its digits. What do you get?
  27. 27.6?17 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.808? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 32 and take away the sum of its digits. What do you get?
  30. 30.?897 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 18 and take away the sum of its digits. What do you get?
  32. 32.Take 59 and take away the sum of its digits. What do you get?
  33. 33.Take 39 and take away the sum of its digits. What do you get?
  34. 34.?220 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.1?54 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 57 and take away the sum of its digits. What do you get?
  37. 37.Take 78 and take away the sum of its digits. What do you get?
  38. 38.3?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 25 and take away the sum of its digits. What do you get?
  40. 40.1?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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