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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 395 · 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.?917 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.45?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.47?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.529? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 21 and take away the sum of its digits. What do you get?
  6. 6.Take 42 and take away the sum of its digits. What do you get?
  7. 7.Take 82 and take away the sum of its digits. What do you get?
  8. 8.26?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?391 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 11 and take away the sum of its digits. What do you get?
  11. 11.644? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 38 and take away the sum of its digits. What do you get?
  13. 13.Take 59 and take away the sum of its digits. What do you get?
  14. 14.Take 84 and take away the sum of its digits. What do you get?
  15. 15.Take 69 and take away the sum of its digits. What do you get?
  16. 16.56?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?337 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.373? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 51 and take away the sum of its digits. What do you get?
  20. 20.?89 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.2?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.6?35 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 35 and take away the sum of its digits. What do you get?
  24. 24.Take 27 and take away the sum of its digits. What do you get?
  25. 25.?165 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 83 and take away the sum of its digits. What do you get?
  27. 27.508? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 58 and take away the sum of its digits. What do you get?
  29. 29.Take 46 and take away the sum of its digits. What do you get?
  30. 30.Take 80 and take away the sum of its digits. What do you get?
  31. 31.?518 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.802? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?582 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.51?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 36 and take away the sum of its digits. What do you get?
  36. 36.?341 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 14 and take away the sum of its digits. What do you get?
  40. 40.761? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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