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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 997 · 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. 1.4?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 16 and take away the sum of its digits. What do you get?
  3. 3.Take 33 and take away the sum of its digits. What do you get?
  4. 4.?236 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 75 and take away the sum of its digits. What do you get?
  6. 6.Take 92 and take away the sum of its digits. What do you get?
  7. 7.Take 55 and take away the sum of its digits. What do you get?
  8. 8.Take 11 and take away the sum of its digits. What do you get?
  9. 9.18?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 44 and take away the sum of its digits. What do you get?
  11. 11.Take 39 and take away the sum of its digits. What do you get?
  12. 12.3?77 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.6?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.15?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 51 and take away the sum of its digits. What do you get?
  16. 16.?883 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?020 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?330 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.4?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.21?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.1?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.27?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 14 and take away the sum of its digits. What do you get?
  25. 25.Take 85 and take away the sum of its digits. What do you get?
  26. 26.529? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.2?27 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.562? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?15 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.201? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.4?94 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 31 and take away the sum of its digits. What do you get?
  34. 34.Take 73 and take away the sum of its digits. What do you get?
  35. 35.Take 42 and take away the sum of its digits. What do you get?
  36. 36.Take 43 and take away the sum of its digits. What do you get?
  37. 37.Take 22 and take away the sum of its digits. What do you get?
  38. 38.Take 63 and take away the sum of its digits. What do you get?
  39. 39.?787 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?169 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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