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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 136 · 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?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 66 and take away the sum of its digits. What do you get?
  3. 3.Take 22 and take away the sum of its digits. What do you get?
  4. 4.46?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 20 and take away the sum of its digits. What do you get?
  6. 6.?804 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?391 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 78 and take away the sum of its digits. What do you get?
  9. 9.804? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 15 and take away the sum of its digits. What do you get?
  11. 11.Take 26 and take away the sum of its digits. What do you get?
  12. 12.55?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 52 and take away the sum of its digits. What do you get?
  14. 14.?077 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?609 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.88?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 30 and take away the sum of its digits. What do you get?
  18. 18.4?52 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.80? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?914 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.59?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.1?15 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 41 and take away the sum of its digits. What do you get?
  24. 24.1?47 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.425? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.7?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 51 and take away the sum of its digits. What do you get?
  28. 28.114? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?316 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 11 and take away the sum of its digits. What do you get?
  31. 31.4?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.2?54 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.2?11 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.80?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.6?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.813? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?838 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.21?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 31 and take away the sum of its digits. What do you get?
  40. 40.Take 54 and take away the sum of its digits. What do you get?

Answer key

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

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