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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 318 · 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.?388 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 93 and take away the sum of its digits. What do you get?
  3. 3.?628 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.93? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 36 and take away the sum of its digits. What do you get?
  6. 6.Take 32 and take away the sum of its digits. What do you get?
  7. 7.Take 53 and take away the sum of its digits. What do you get?
  8. 8.54?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.479? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 14 and take away the sum of its digits. What do you get?
  11. 11.Take 15 and take away the sum of its digits. What do you get?
  12. 12.25?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.71?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.267? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 27 and take away the sum of its digits. What do you get?
  16. 16.Take 57 and take away the sum of its digits. What do you get?
  17. 17.26?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.58?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.6?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 24 and take away the sum of its digits. What do you get?
  21. 21.745? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 39 and take away the sum of its digits. What do you get?
  23. 23.346? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 83 and take away the sum of its digits. What do you get?
  25. 25.?472 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?132 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.52?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.706? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?904 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.5?08 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.462? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 55 and take away the sum of its digits. What do you get?
  33. 33.Take 73 and take away the sum of its digits. What do you get?
  34. 34.Take 12 and take away the sum of its digits. What do you get?
  35. 35.62?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.176? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 21 and take away the sum of its digits. What do you get?
  38. 38.Take 80 and take away the sum of its digits. What do you get?
  39. 39.77?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?58 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. 81
  3. 2
  4. 6
  5. 27
  6. 27
  7. 45
  8. 8
  9. 7
  10. 9
  11. 9
  12. 2
  13. 9
  14. 3
  15. 18
  16. 45
  17. 6
  18. 1
  19. 3
  20. 18
  21. 2
  22. 27
  23. 5
  24. 72
  25. 5
  26. 3
  27. 3
  28. 5
  29. 5
  30. 5
  31. 6
  32. 45
  33. 63
  34. 9
  35. 7
  36. 4
  37. 18
  38. 72
  39. 9
  40. 5

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