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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 653 · 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. 1.50?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.820? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 18 and take away the sum of its digits. What do you get?
  4. 4.?473 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.7?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 86 and take away the sum of its digits. What do you get?
  7. 7.Take 29 and take away the sum of its digits. What do you get?
  8. 8.Take 16 and take away the sum of its digits. What do you get?
  9. 9.Take 85 and take away the sum of its digits. What do you get?
  10. 10.Take 94 and take away the sum of its digits. What do you get?
  11. 11.715? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.8?39 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 54 and take away the sum of its digits. What do you get?
  14. 14.Take 66 and take away the sum of its digits. What do you get?
  15. 15.Take 24 and take away the sum of its digits. What do you get?
  16. 16.6?81 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.37? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.33?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?001 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?023 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.52?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 78 and take away the sum of its digits. What do you get?
  23. 23.232? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 42 and take away the sum of its digits. What do you get?
  25. 25.1?33 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 74 and take away the sum of its digits. What do you get?
  27. 27.Take 39 and take away the sum of its digits. What do you get?
  28. 28.327? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?291 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.8?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?398 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.20?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 82 and take away the sum of its digits. What do you get?
  34. 34.4?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.59?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.258? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.6?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.1?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.882? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?705 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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