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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 922 · 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.?851 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.306? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 62 and take away the sum of its digits. What do you get?
  4. 4.201? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 68 and take away the sum of its digits. What do you get?
  6. 6.130? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.5?35 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?830 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 29 and take away the sum of its digits. What do you get?
  10. 10.35?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 78 and take away the sum of its digits. What do you get?
  12. 12.1?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.76?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.13?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.54?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.469? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.10?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.6?54 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 28 and take away the sum of its digits. What do you get?
  20. 20.?81 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.366? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 63 and take away the sum of its digits. What do you get?
  23. 23.Take 98 and take away the sum of its digits. What do you get?
  24. 24.87?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.8?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 52 and take away the sum of its digits. What do you get?
  27. 27.Take 61 and take away the sum of its digits. What do you get?
  28. 28.?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?125 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.3?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.8?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 85 and take away the sum of its digits. What do you get?
  33. 33.Take 12 and take away the sum of its digits. What do you get?
  34. 34.2?93 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.1?89 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 43 and take away the sum of its digits. What do you get?
  37. 37.87?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.727? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?714 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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