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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 149 · 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.?011 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?520 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.602? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 17 and take away the sum of its digits. What do you get?
  5. 5.Take 91 and take away the sum of its digits. What do you get?
  6. 6.Take 31 and take away the sum of its digits. What do you get?
  7. 7.?029 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 60 and take away the sum of its digits. What do you get?
  9. 9.2?78 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 67 and take away the sum of its digits. What do you get?
  11. 11.27?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 34 and take away the sum of its digits. What do you get?
  13. 13.Take 22 and take away the sum of its digits. What do you get?
  14. 14.Take 51 and take away the sum of its digits. What do you get?
  15. 15.?602 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 80 and take away the sum of its digits. What do you get?
  17. 17.573? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.1?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?568 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.53? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.68?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 94 and take away the sum of its digits. What do you get?
  23. 23.745? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 25 and take away the sum of its digits. What do you get?
  25. 25.Take 50 and take away the sum of its digits. What do you get?
  26. 26.Take 27 and take away the sum of its digits. What do you get?
  27. 27.2?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.41?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?586 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.23? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.76?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 72 and take away the sum of its digits. What do you get?
  33. 33.759? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.56? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.6?14 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.10?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 73 and take away the sum of its digits. What do you get?
  38. 38.1?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.34?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 29 and take away the sum of its digits. What do you get?

Answer key

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

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