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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 203 · 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 92 and take away the sum of its digits. What do you get?
  2. 2.145? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?746 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?172 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.312? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.333? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.57?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 67 and take away the sum of its digits. What do you get?
  10. 10.476? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?744 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.66?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?419 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 21 and take away the sum of its digits. What do you get?
  15. 15.?646 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 59 and take away the sum of its digits. What do you get?
  17. 17.Take 79 and take away the sum of its digits. What do you get?
  18. 18.Take 66 and take away the sum of its digits. What do you get?
  19. 19.651? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.7?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 99 and take away the sum of its digits. What do you get?
  22. 22.?624 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.1?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.63?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 50 and take away the sum of its digits. What do you get?
  26. 26.?155 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.415? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.1?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.6?29 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?094 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?796 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.7?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.22? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 68 and take away the sum of its digits. What do you get?
  35. 35.?27 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?85 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.525? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?867 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 83 and take away the sum of its digits. What do you get?
  40. 40.Take 95 and take away the sum of its digits. What do you get?

Answer key

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

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