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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 913 · 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. 1.77? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?623 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.5?07 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.55?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.6?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 29 and take away the sum of its digits. What do you get?
  7. 7.5?43 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?59 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.104? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.304? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?291 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.44?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?429 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?170 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 69 and take away the sum of its digits. What do you get?
  16. 16.18?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.88? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 86 and take away the sum of its digits. What do you get?
  19. 19.?659 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?52 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.275? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 13 and take away the sum of its digits. What do you get?
  23. 23.468? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 95 and take away the sum of its digits. What do you get?
  25. 25.?222 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.26?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.89?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 49 and take away the sum of its digits. What do you get?
  29. 29.Take 84 and take away the sum of its digits. What do you get?
  30. 30.1?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 12 and take away the sum of its digits. What do you get?
  32. 32.Take 41 and take away the sum of its digits. What do you get?
  33. 33.8?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 91 and take away the sum of its digits. What do you get?
  35. 35.?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.24?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.51?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.25?5 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.Take 35 and take away the sum of its digits. What do you get?

Answer key

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

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