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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 263 · 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. 1.805? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 67 and take away the sum of its digits. What do you get?
  3. 3.Take 21 and take away the sum of its digits. What do you get?
  4. 4.433? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.31?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 88 and take away the sum of its digits. What do you get?
  7. 7.Take 53 and take away the sum of its digits. What do you get?
  8. 8.?448 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?052 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?619 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.18?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.877? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.15? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.200? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.658? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 84 and take away the sum of its digits. What do you get?
  17. 17.146? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 65 and take away the sum of its digits. What do you get?
  19. 19.?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?254 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 73 and take away the sum of its digits. What do you get?
  22. 22.42?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.12?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 23 and take away the sum of its digits. What do you get?
  25. 25.Take 44 and take away the sum of its digits. What do you get?
  26. 26.605? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 99 and take away the sum of its digits. What do you get?
  28. 28.15?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 17 and take away the sum of its digits. What do you get?
  30. 30.Take 12 and take away the sum of its digits. What do you get?
  31. 31.400? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.556? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 29 and take away the sum of its digits. What do you get?
  34. 34.Take 37 and take away the sum of its digits. What do you get?
  35. 35.55?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.692? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.43? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?920 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 42 and take away the sum of its digits. What do you get?
  40. 40.Take 89 and take away the sum of its digits. What do you get?

Answer key

  1. 5
  2. 54
  3. 18
  4. 8
  5. 4
  6. 72
  7. 45
  8. 2
  9. 2
  10. 2
  11. 2
  12. 5
  13. 3
  14. 7
  15. 8
  16. 72
  17. 7
  18. 54
  19. 2
  20. 7
  21. 63
  22. 5
  23. 1
  24. 18
  25. 36
  26. 7
  27. 81
  28. 6
  29. 9
  30. 9
  31. 5
  32. 2
  33. 18
  34. 27
  35. 4
  36. 1
  37. 2
  38. 7
  39. 36
  40. 72

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