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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 971 · 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.Take 80 and take away the sum of its digits. What do you get?
  2. 2.9?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?103 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?276 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?949 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.76?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.25?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 78 and take away the sum of its digits. What do you get?
  9. 9.849? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 53 and take away the sum of its digits. What do you get?
  11. 11.Take 94 and take away the sum of its digits. What do you get?
  12. 12.3?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 30 and take away the sum of its digits. What do you get?
  14. 14.5?44 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 54 and take away the sum of its digits. What do you get?
  16. 16.Take 76 and take away the sum of its digits. What do you get?
  17. 17.7?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 47 and take away the sum of its digits. What do you get?
  19. 19.?510 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.6?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.2?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.8?81 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.8?39 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.6?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?856 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?088 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 14 and take away the sum of its digits. What do you get?
  28. 28.Take 91 and take away the sum of its digits. What do you get?
  29. 29.Take 16 and take away the sum of its digits. What do you get?
  30. 30.Take 92 and take away the sum of its digits. What do you get?
  31. 31.Take 44 and take away the sum of its digits. What do you get?
  32. 32.Take 26 and take away the sum of its digits. What do you get?
  33. 33.Take 29 and take away the sum of its digits. What do you get?
  34. 34.76?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 36 and take away the sum of its digits. What do you get?
  36. 36.3?36 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.828? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.730? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 35 and take away the sum of its digits. What do you get?
  40. 40.17?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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