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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 780 · 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.?173 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?717 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.13?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?213 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 28 and take away the sum of its digits. What do you get?
  6. 6.5?28 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?494 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.6?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?003 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.19?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 91 and take away the sum of its digits. What do you get?
  12. 12.Take 59 and take away the sum of its digits. What do you get?
  13. 13.Take 26 and take away the sum of its digits. What do you get?
  14. 14.Take 65 and take away the sum of its digits. What do you get?
  15. 15.841? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 22 and take away the sum of its digits. What do you get?
  17. 17.Take 14 and take away the sum of its digits. What do you get?
  18. 18.43?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.20?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?239 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.6?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.3?75 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?95 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?767 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 29 and take away the sum of its digits. What do you get?
  26. 26.225? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 44 and take away the sum of its digits. What do you get?
  28. 28.3?69 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 80 and take away the sum of its digits. What do you get?
  30. 30.?527 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 85 and take away the sum of its digits. What do you get?
  32. 32.Take 16 and take away the sum of its digits. What do you get?
  33. 33.8?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 66 and take away the sum of its digits. What do you get?
  35. 35.Take 39 and take away the sum of its digits. What do you get?
  36. 36.?804 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.751? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?48 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 20 and take away the sum of its digits. What do you get?
  40. 40.Take 45 and take away the sum of its digits. What do you get?

Answer key

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

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