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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 343 · 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 85 and take away the sum of its digits. What do you get?
  2. 2.3?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 20 and take away the sum of its digits. What do you get?
  4. 4.?993 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 50 and take away the sum of its digits. What do you get?
  6. 6.574? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 78 and take away the sum of its digits. What do you get?
  8. 8.Take 39 and take away the sum of its digits. What do you get?
  9. 9.?940 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?551 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?053 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 74 and take away the sum of its digits. What do you get?
  13. 13.Take 83 and take away the sum of its digits. What do you get?
  14. 14.Take 30 and take away the sum of its digits. What do you get?
  15. 15.6?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.720? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.1?08 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 19 and take away the sum of its digits. What do you get?
  19. 19.568? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 46 and take away the sum of its digits. What do you get?
  21. 21.1?89 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.2?48 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.431? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.28?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.487? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?505 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.47? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.70?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?328 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 63 and take away the sum of its digits. What do you get?
  31. 31.53?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.6?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 68 and take away the sum of its digits. What do you get?
  34. 34.Take 86 and take away the sum of its digits. What do you get?
  35. 35.14?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 91 and take away the sum of its digits. What do you get?
  37. 37.1?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.73?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?167 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.842? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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