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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 986 · 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.Take 79 and take away the sum of its digits. What do you get?
  2. 2.Take 53 and take away the sum of its digits. What do you get?
  3. 3.?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 12 and take away the sum of its digits. What do you get?
  5. 5.?942 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.847? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 83 and take away the sum of its digits. What do you get?
  8. 8.34?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?203 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.38?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?184 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 84 and take away the sum of its digits. What do you get?
  13. 13.136? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.11?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.1?32 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?391 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.660? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 99 and take away the sum of its digits. What do you get?
  19. 19.7?98 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.89?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?251 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.82?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?925 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.70?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.61? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?101 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?758 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.50?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 52 and take away the sum of its digits. What do you get?
  30. 30.630? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.2?14 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?704 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 22 and take away the sum of its digits. What do you get?
  35. 35.?54 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?395 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 13 and take away the sum of its digits. What do you get?
  38. 38.4?17 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 59 and take away the sum of its digits. What do you get?
  40. 40.131? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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