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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 568 · 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. 1.3?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 69 and take away the sum of its digits. What do you get?
  3. 3.Take 81 and take away the sum of its digits. What do you get?
  4. 4.?239 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 60 and take away the sum of its digits. What do you get?
  6. 6.646? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 87 and take away the sum of its digits. What do you get?
  8. 8.5?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.30?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?752 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.454? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 21 and take away the sum of its digits. What do you get?
  13. 13.Take 94 and take away the sum of its digits. What do you get?
  14. 14.Take 70 and take away the sum of its digits. What do you get?
  15. 15.1?86 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?097 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.5?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?713 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.1?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.8?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 44 and take away the sum of its digits. What do you get?
  23. 23.?761 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 34 and take away the sum of its digits. What do you get?
  25. 25.Take 47 and take away the sum of its digits. What do you get?
  26. 26.31? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.44?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?156 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.39?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.57?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 36 and take away the sum of its digits. What do you get?
  33. 33.Take 40 and take away the sum of its digits. What do you get?
  34. 34.2?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 16 and take away the sum of its digits. What do you get?
  36. 36.?695 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 61 and take away the sum of its digits. What do you get?
  38. 38.Take 32 and take away the sum of its digits. What do you get?
  39. 39.?178 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?899 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. 54
  3. 72
  4. 4
  5. 54
  6. 2
  7. 72
  8. 8
  9. 6
  10. 4
  11. 5
  12. 18
  13. 81
  14. 63
  15. 3
  16. 2
  17. 3
  18. 6
  19. 7
  20. 3
  21. 1
  22. 36
  23. 4
  24. 27
  25. 36
  26. 5
  27. 3
  28. 3
  29. 6
  30. 6
  31. 1
  32. 27
  33. 36
  34. 5
  35. 9
  36. 7
  37. 54
  38. 27
  39. 2
  40. 1

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