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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 860 · 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. 1.228? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 20 and take away the sum of its digits. What do you get?
  3. 3.23?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.88?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.1?07 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.28?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.707? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 98 and take away the sum of its digits. What do you get?
  9. 9.48?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?929 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.674? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?076 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.6?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.6?44 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.664? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.6?67 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 15 and take away the sum of its digits. What do you get?
  18. 18.?400 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.7?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.2?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.20? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?444 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 64 and take away the sum of its digits. What do you get?
  24. 24.1?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 21 and take away the sum of its digits. What do you get?
  26. 26.13?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?107 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.66?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 86 and take away the sum of its digits. What do you get?
  30. 30.Take 75 and take away the sum of its digits. What do you get?
  31. 31.201? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 80 and take away the sum of its digits. What do you get?
  33. 33.Take 42 and take away the sum of its digits. What do you get?
  34. 34.802? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.6?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.8?07 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.80?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.51?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 65 and take away the sum of its digits. What do you get?
  40. 40.70?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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