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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 919 · 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. 1.89?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 23 and take away the sum of its digits. What do you get?
  3. 3.8?55 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.8?17 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.4?75 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.8?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 70 and take away the sum of its digits. What do you get?
  8. 8.?924 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.706? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?464 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 22 and take away the sum of its digits. What do you get?
  12. 12.?708 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.9?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?205 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?304 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.6?91 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 64 and take away the sum of its digits. What do you get?
  18. 18.Take 77 and take away the sum of its digits. What do you get?
  19. 19.670? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.84? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 52 and take away the sum of its digits. What do you get?
  22. 22.Take 38 and take away the sum of its digits. What do you get?
  23. 23.Take 81 and take away the sum of its digits. What do you get?
  24. 24.Take 72 and take away the sum of its digits. What do you get?
  25. 25.256? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.10?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.41?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 13 and take away the sum of its digits. What do you get?
  29. 29.?475 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.501? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 89 and take away the sum of its digits. What do you get?
  32. 32.14?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.30?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 73 and take away the sum of its digits. What do you get?
  35. 35.?779 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.1?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 68 and take away the sum of its digits. What do you get?
  38. 38.473? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?95 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 90 and take away the sum of its digits. What do you get?

Answer key

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

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