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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 836 · 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. 1.14?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 40 and take away the sum of its digits. What do you get?
  3. 3.Take 73 and take away the sum of its digits. What do you get?
  4. 4.?275 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 30 and take away the sum of its digits. What do you get?
  6. 6.?583 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 32 and take away the sum of its digits. What do you get?
  8. 8.62?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 36 and take away the sum of its digits. What do you get?
  10. 10.Take 72 and take away the sum of its digits. What do you get?
  11. 11.Take 91 and take away the sum of its digits. What do you get?
  12. 12.?599 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 82 and take away the sum of its digits. What do you get?
  14. 14.Take 90 and take away the sum of its digits. What do you get?
  15. 15.8?71 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.4?22 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.30? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 87 and take away the sum of its digits. What do you get?
  19. 19.8?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.1?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.84? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 53 and take away the sum of its digits. What do you get?
  24. 24.1?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.2?98 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 98 and take away the sum of its digits. What do you get?
  27. 27.358? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.5?17 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.3?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.1?47 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?501 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.8?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 26 and take away the sum of its digits. What do you get?
  34. 34.4?63 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 33 and take away the sum of its digits. What do you get?
  36. 36.?179 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?109 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 24 and take away the sum of its digits. What do you get?
  39. 39.Take 27 and take away the sum of its digits. What do you get?
  40. 40.70? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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