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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 195 · 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 47 and take away the sum of its digits. What do you get?
  2. 2.Take 79 and take away the sum of its digits. What do you get?
  3. 3.Take 56 and take away the sum of its digits. What do you get?
  4. 4.?658 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?803 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.29?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.48?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.7?83 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.473? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.80?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.139? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?321 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.6?26 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.83?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.7?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?931 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.5?39 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.582? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 64 and take away the sum of its digits. What do you get?
  20. 20.5?62 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.172? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.706? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.2?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?005 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.7?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?753 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 45 and take away the sum of its digits. What do you get?
  28. 28.446? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.588? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 78 and take away the sum of its digits. What do you get?
  31. 31.4?55 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.8?35 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 33 and take away the sum of its digits. What do you get?
  34. 34.Take 36 and take away the sum of its digits. What do you get?
  35. 35.?852 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 14 and take away the sum of its digits. What do you get?
  37. 37.Take 75 and take away the sum of its digits. What do you get?
  38. 38.?734 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?694 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.765? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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