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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 250 · 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. 1.8?57 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?980 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 31 and take away the sum of its digits. What do you get?
  4. 4.Take 49 and take away the sum of its digits. What do you get?
  5. 5.?325 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?993 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.2?33 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?502 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.404? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 19 and take away the sum of its digits. What do you get?
  11. 11.24?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.812? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.299? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.4?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.23? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.23?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 40 and take away the sum of its digits. What do you get?
  18. 18.?505 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.617? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.53?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?097 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.308? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.5?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 86 and take away the sum of its digits. What do you get?
  25. 25.21?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 93 and take away the sum of its digits. What do you get?
  27. 27.Take 92 and take away the sum of its digits. What do you get?
  28. 28.34?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.1?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.25?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?390 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.7?84 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.47?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 59 and take away the sum of its digits. What do you get?
  35. 35.?115 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 25 and take away the sum of its digits. What do you get?
  37. 37.44?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.758? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?445 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 95 and take away the sum of its digits. What do you get?

Answer key

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

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