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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 664 · 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.Take 39 and take away the sum of its digits. What do you get?
  2. 2.25?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?300 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?347 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.56?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.252? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.2?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 95 and take away the sum of its digits. What do you get?
  9. 9.Take 58 and take away the sum of its digits. What do you get?
  10. 10.?555 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.98? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 47 and take away the sum of its digits. What do you get?
  13. 13.Take 21 and take away the sum of its digits. What do you get?
  14. 14.Take 24 and take away the sum of its digits. What do you get?
  15. 15.Take 41 and take away the sum of its digits. What do you get?
  16. 16.53? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.627? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.7?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?303 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 36 and take away the sum of its digits. What do you get?
  22. 22.14?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?181 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 92 and take away the sum of its digits. What do you get?
  25. 25.44?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.6?42 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.391? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 38 and take away the sum of its digits. What do you get?
  29. 29.Take 97 and take away the sum of its digits. What do you get?
  30. 30.Take 76 and take away the sum of its digits. What do you get?
  31. 31.Take 98 and take away the sum of its digits. What do you get?
  32. 32.80?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.12? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?502 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 15 and take away the sum of its digits. What do you get?
  36. 36.?376 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.8?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.6?45 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?103 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.813? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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