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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 228 · 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.?298 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?238 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.209? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 96 and take away the sum of its digits. What do you get?
  5. 5.Take 89 and take away the sum of its digits. What do you get?
  6. 6.Take 40 and take away the sum of its digits. What do you get?
  7. 7.370? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?16 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?145 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 57 and take away the sum of its digits. What do you get?
  11. 11.?898 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.27?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.557? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.890? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.72?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?703 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.255? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?017 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?227 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 54 and take away the sum of its digits. What do you get?
  21. 21.Take 12 and take away the sum of its digits. What do you get?
  22. 22.2?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.39?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.76?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.761? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?201 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 46 and take away the sum of its digits. What do you get?
  28. 28.19?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?331 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.1?94 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.884? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 23 and take away the sum of its digits. What do you get?
  33. 33.1?45 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?28 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 90 and take away the sum of its digits. What do you get?
  37. 37.Take 85 and take away the sum of its digits. What do you get?
  38. 38.Take 94 and take away the sum of its digits. What do you get?
  39. 39.Take 21 and take away the sum of its digits. What do you get?
  40. 40.88?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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