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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 751 · 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.?440 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?933 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.74? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.802? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 23 and take away the sum of its digits. What do you get?
  7. 7.1?17 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 86 and take away the sum of its digits. What do you get?
  9. 9.?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 96 and take away the sum of its digits. What do you get?
  11. 11.Take 38 and take away the sum of its digits. What do you get?
  12. 12.Take 14 and take away the sum of its digits. What do you get?
  13. 13.624? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.360? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 17 and take away the sum of its digits. What do you get?
  16. 16.Take 21 and take away the sum of its digits. What do you get?
  17. 17.Take 63 and take away the sum of its digits. What do you get?
  18. 18.?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.5?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.3?75 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.6?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.6?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.59?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.43?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.811? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.5?64 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 82 and take away the sum of its digits. What do you get?
  30. 30.Take 20 and take away the sum of its digits. What do you get?
  31. 31.?802 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?95 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.398? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 81 and take away the sum of its digits. What do you get?
  35. 35.?436 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?064 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.3?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 58 and take away the sum of its digits. What do you get?
  39. 39.Take 36 and take away the sum of its digits. What do you get?
  40. 40.Take 56 and take away the sum of its digits. What do you get?

Answer key

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

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