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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 585 · 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.?046 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.82?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.60?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?168 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.303? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?845 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.61?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?479 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.100? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.575? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.7?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.60? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 40 and take away the sum of its digits. What do you get?
  14. 14.Take 39 and take away the sum of its digits. What do you get?
  15. 15.?253 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 15 and take away the sum of its digits. What do you get?
  17. 17.Take 54 and take away the sum of its digits. What do you get?
  18. 18.Take 19 and take away the sum of its digits. What do you get?
  19. 19.32?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.38?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 44 and take away the sum of its digits. What do you get?
  22. 22.Take 27 and take away the sum of its digits. What do you get?
  23. 23.?780 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 82 and take away the sum of its digits. What do you get?
  25. 25.Take 78 and take away the sum of its digits. What do you get?
  26. 26.30?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.191? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 91 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 21 and take away the sum of its digits. What do you get?
  31. 31.?901 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 59 and take away the sum of its digits. What do you get?
  33. 33.Take 38 and take away the sum of its digits. What do you get?
  34. 34.317? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?149 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.3?27 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?169 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.1?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 33 and take away the sum of its digits. What do you get?
  40. 40.51?1 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. 2
  4. 3
  5. 3
  6. 1
  7. 4
  8. 7
  9. 8
  10. 1
  11. 4
  12. 3
  13. 36
  14. 27
  15. 8
  16. 9
  17. 45
  18. 9
  19. 4
  20. 6
  21. 36
  22. 18
  23. 3
  24. 72
  25. 63
  26. 9
  27. 7
  28. 81
  29. 36
  30. 18
  31. 8
  32. 45
  33. 27
  34. 7
  35. 4
  36. 6
  37. 2
  38. 3
  39. 27
  40. 2

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