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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 357 · 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 20 and take away the sum of its digits. What do you get?
  2. 2.2?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.508? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.61?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.151? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?474 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 21 and take away the sum of its digits. What do you get?
  8. 8.Take 30 and take away the sum of its digits. What do you get?
  9. 9.Take 51 and take away the sum of its digits. What do you get?
  10. 10.47?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 53 and take away the sum of its digits. What do you get?
  12. 12.?269 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 23 and take away the sum of its digits. What do you get?
  14. 14.8?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.77?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?390 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.37?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.506? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.2?55 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?381 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?043 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 24 and take away the sum of its digits. What do you get?
  24. 24.580? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 17 and take away the sum of its digits. What do you get?
  26. 26.?26 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.12?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.6?39 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?69 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 35 and take away the sum of its digits. What do you get?
  31. 31.Take 26 and take away the sum of its digits. What do you get?
  32. 32.300? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.65?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?462 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.36?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 90 and take away the sum of its digits. What do you get?
  37. 37.Take 92 and take away the sum of its digits. What do you get?
  38. 38.80?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 39 and take away the sum of its digits. What do you get?
  40. 40.7?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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