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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 579 · 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.?910 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.589? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?329 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.7?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.62?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.251? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.103? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 31 and take away the sum of its digits. What do you get?
  9. 9.7?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.595? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 27 and take away the sum of its digits. What do you get?
  12. 12.Take 94 and take away the sum of its digits. What do you get?
  13. 13.?592 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 24 and take away the sum of its digits. What do you get?
  15. 15.Take 21 and take away the sum of its digits. What do you get?
  16. 16.Take 43 and take away the sum of its digits. What do you get?
  17. 17.Take 39 and take away the sum of its digits. What do you get?
  18. 18.17?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.702? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?449 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 18 and take away the sum of its digits. What do you get?
  22. 22.2?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?537 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?842 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 34 and take away the sum of its digits. What do you get?
  26. 26.5?91 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?303 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 23 and take away the sum of its digits. What do you get?
  29. 29.67?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 86 and take away the sum of its digits. What do you get?
  31. 31.Take 46 and take away the sum of its digits. What do you get?
  32. 32.537? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.654? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.128? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 52 and take away the sum of its digits. What do you get?
  36. 36.7?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 16 and take away the sum of its digits. What do you get?
  38. 38.42?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?370 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 82 and take away the sum of its digits. What do you get?

Answer key

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

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