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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 171 · 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. 1.5?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 88 and take away the sum of its digits. What do you get?
  3. 3.730? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 98 and take away the sum of its digits. What do you get?
  5. 5.Take 48 and take away the sum of its digits. What do you get?
  6. 6.Take 56 and take away the sum of its digits. What do you get?
  7. 7.Take 16 and take away the sum of its digits. What do you get?
  8. 8.456? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.43?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?113 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.5?68 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?086 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 77 and take away the sum of its digits. What do you get?
  14. 14.8?63 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 74 and take away the sum of its digits. What do you get?
  16. 16.?85 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 52 and take away the sum of its digits. What do you get?
  18. 18.Take 36 and take away the sum of its digits. What do you get?
  19. 19.8?14 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 12 and take away the sum of its digits. What do you get?
  21. 21.Take 35 and take away the sum of its digits. What do you get?
  22. 22.Take 71 and take away the sum of its digits. What do you get?
  23. 23.45?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?735 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.6?72 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.819? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.4?64 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?502 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.849? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 31 and take away the sum of its digits. What do you get?
  31. 31.7?01 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.2?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 75 and take away the sum of its digits. What do you get?
  34. 34.?970 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.56?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?92 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?833 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.2?44 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 21 and take away the sum of its digits. What do you get?
  40. 40.83?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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