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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 701 · 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. 1.669? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 19 and take away the sum of its digits. What do you get?
  3. 3.Take 90 and take away the sum of its digits. What do you get?
  4. 4.Take 43 and take away the sum of its digits. What do you get?
  5. 5.8?91 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 80 and take away the sum of its digits. What do you get?
  7. 7.528? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.2?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.3?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?272 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 72 and take away the sum of its digits. What do you get?
  12. 12.Take 22 and take away the sum of its digits. What do you get?
  13. 13.Take 42 and take away the sum of its digits. What do you get?
  14. 14.2?92 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.79?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 17 and take away the sum of its digits. What do you get?
  17. 17.5?26 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?395 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 40 and take away the sum of its digits. What do you get?
  20. 20.6?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 14 and take away the sum of its digits. What do you get?
  22. 22.1?74 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.534? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.4?86 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?469 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.7?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 60 and take away the sum of its digits. What do you get?
  28. 28.Take 20 and take away the sum of its digits. What do you get?
  29. 29.?559 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 34 and take away the sum of its digits. What do you get?
  31. 31.65?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 85 and take away the sum of its digits. What do you get?
  33. 33.?731 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.87? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.9?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?016 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 49 and take away the sum of its digits. What do you get?
  38. 38.635? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 91 and take away the sum of its digits. What do you get?
  40. 40.Take 61 and take away the sum of its digits. What do you get?

Answer key

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

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