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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 88 · 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. 1.7?27 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.822? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 25 and take away the sum of its digits. What do you get?
  4. 4.45?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 77 and take away the sum of its digits. What do you get?
  6. 6.Take 17 and take away the sum of its digits. What do you get?
  7. 7.372? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 40 and take away the sum of its digits. What do you get?
  9. 9.Take 80 and take away the sum of its digits. What do you get?
  10. 10.Take 76 and take away the sum of its digits. What do you get?
  11. 11.6?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?898 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.71?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.36?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.77?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 24 and take away the sum of its digits. What do you get?
  17. 17.3?91 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 22 and take away the sum of its digits. What do you get?
  19. 19.Take 36 and take away the sum of its digits. What do you get?
  20. 20.82?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.3?72 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?674 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?670 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 89 and take away the sum of its digits. What do you get?
  25. 25.Take 48 and take away the sum of its digits. What do you get?
  26. 26.201? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 74 and take away the sum of its digits. What do you get?
  28. 28.Take 37 and take away the sum of its digits. What do you get?
  29. 29.59? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.8?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.6?92 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.3?82 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.3?41 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.7?74 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.27?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?366 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.45?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.7?61 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 59 and take away the sum of its digits. What do you get?
  40. 40.6?16 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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