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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 194 · 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.Take 17 and take away the sum of its digits. What do you get?
  2. 2.53?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 61 and take away the sum of its digits. What do you get?
  4. 4.?926 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 82 and take away the sum of its digits. What do you get?
  6. 6.Take 23 and take away the sum of its digits. What do you get?
  7. 7.Take 69 and take away the sum of its digits. What do you get?
  8. 8.48?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?784 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.16? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 59 and take away the sum of its digits. What do you get?
  12. 12.Take 22 and take away the sum of its digits. What do you get?
  13. 13.Take 81 and take away the sum of its digits. What do you get?
  14. 14.Take 40 and take away the sum of its digits. What do you get?
  15. 15.4?85 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.2?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 28 and take away the sum of its digits. What do you get?
  18. 18.695? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 63 and take away the sum of its digits. What do you get?
  20. 20.Take 37 and take away the sum of its digits. What do you get?
  21. 21.30?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?134 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.3?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 78 and take away the sum of its digits. What do you get?
  25. 25.?448 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.504? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 79 and take away the sum of its digits. What do you get?
  28. 28.Take 45 and take away the sum of its digits. What do you get?
  29. 29.?338 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 99 and take away the sum of its digits. What do you get?
  31. 31.76?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.39?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.8?63 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 71 and take away the sum of its digits. What do you get?
  35. 35.81?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.830? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.38?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.539? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 76 and take away the sum of its digits. What do you get?
  40. 40.Take 16 and take away the sum of its digits. What do you get?

Answer key

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

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