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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 223 · 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. 1.164? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?78 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.1?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.3?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?690 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.4?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.400? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 11 and take away the sum of its digits. What do you get?
  9. 9.28?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 72 and take away the sum of its digits. What do you get?
  11. 11.?803 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?716 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 47 and take away the sum of its digits. What do you get?
  14. 14.Take 35 and take away the sum of its digits. What do you get?
  15. 15.Take 80 and take away the sum of its digits. What do you get?
  16. 16.848? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 58 and take away the sum of its digits. What do you get?
  18. 18.Take 32 and take away the sum of its digits. What do you get?
  19. 19.26?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.5?77 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.6?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 18 and take away the sum of its digits. What do you get?
  23. 23.Take 70 and take away the sum of its digits. What do you get?
  24. 24.5?14 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.116? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.40?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?323 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.240? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 91 and take away the sum of its digits. What do you get?
  30. 30.42?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.413? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.32?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 77 and take away the sum of its digits. What do you get?
  34. 34.81?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?328 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.70?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 98 and take away the sum of its digits. What do you get?
  38. 38.?742 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 57 and take away the sum of its digits. What do you get?
  40. 40.?600 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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