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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 176 · 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. 1.79?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.7?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.4?48 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 17 and take away the sum of its digits. What do you get?
  5. 5.Take 47 and take away the sum of its digits. What do you get?
  6. 6.?087 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 51 and take away the sum of its digits. What do you get?
  8. 8.3?32 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.2?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 42 and take away the sum of its digits. What do you get?
  11. 11.Take 24 and take away the sum of its digits. What do you get?
  12. 12.87?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 67 and take away the sum of its digits. What do you get?
  14. 14.66? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.17?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 74 and take away the sum of its digits. What do you get?
  17. 17.10?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.546? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 82 and take away the sum of its digits. What do you get?
  20. 20.561? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.534? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 21 and take away the sum of its digits. What do you get?
  23. 23.?578 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 58 and take away the sum of its digits. What do you get?
  25. 25.?201 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.807? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?528 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.3?27 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?879 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.208? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.369? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.1?81 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 53 and take away the sum of its digits. What do you get?
  34. 34.Take 18 and take away the sum of its digits. What do you get?
  35. 35.729? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 27 and take away the sum of its digits. What do you get?
  37. 37.?893 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?596 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 72 and take away the sum of its digits. What do you get?
  40. 40.?787 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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