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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 102 · 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. 1.89?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 97 and take away the sum of its digits. What do you get?
  3. 3.?904 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.141? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 35 and take away the sum of its digits. What do you get?
  6. 6.?744 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 33 and take away the sum of its digits. What do you get?
  8. 8.?002 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.66?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?217 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.35? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.1?40 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.?620 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?059 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.555? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?380 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.8?23 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 55 and take away the sum of its digits. What do you get?
  20. 20.75?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 61 and take away the sum of its digits. What do you get?
  22. 22.Take 38 and take away the sum of its digits. What do you get?
  23. 23.Take 62 and take away the sum of its digits. What do you get?
  24. 24.6?45 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 36 and take away the sum of its digits. What do you get?
  26. 26.Take 45 and take away the sum of its digits. What do you get?
  27. 27.Take 71 and take away the sum of its digits. What do you get?
  28. 28.?922 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.4?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.3?54 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 92 and take away the sum of its digits. What do you get?
  32. 32.Take 19 and take away the sum of its digits. What do you get?
  33. 33.Take 72 and take away the sum of its digits. What do you get?
  34. 34.Take 15 and take away the sum of its digits. What do you get?
  35. 35.4?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 23 and take away the sum of its digits. What do you get?
  37. 37.2?53 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 12 and take away the sum of its digits. What do you get?
  39. 39.?739 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 86 and take away the sum of its digits. What do you get?

Answer key

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

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