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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 305 · 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. 1.21?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.286? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 74 and take away the sum of its digits. What do you get?
  4. 4.?511 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 96 and take away the sum of its digits. What do you get?
  6. 6.Take 18 and take away the sum of its digits. What do you get?
  7. 7.76?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.8?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.70?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.51?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.342? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.73?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.35?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?106 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?782 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.74?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 85 and take away the sum of its digits. What do you get?
  18. 18.6?69 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.7?75 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 63 and take away the sum of its digits. What do you get?
  21. 21.748? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.6?59 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.82?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.79? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 14 and take away the sum of its digits. What do you get?
  26. 26.Take 40 and take away the sum of its digits. What do you get?
  27. 27.568? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.26?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 30 and take away the sum of its digits. What do you get?
  30. 30.652? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 17 and take away the sum of its digits. What do you get?
  32. 32.Take 38 and take away the sum of its digits. What do you get?
  33. 33.78?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.3?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 53 and take away the sum of its digits. What do you get?
  36. 36.Take 93 and take away the sum of its digits. What do you get?
  37. 37.Take 43 and take away the sum of its digits. What do you get?
  38. 38.Take 67 and take away the sum of its digits. What do you get?
  39. 39.?623 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.36?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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