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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 49 · 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 84 and take away the sum of its digits. What do you get?
  2. 2.Take 94 and take away the sum of its digits. What do you get?
  3. 3.5?72 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?07 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.163? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 70 and take away the sum of its digits. What do you get?
  7. 7.5?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 68 and take away the sum of its digits. What do you get?
  9. 9.284? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.382? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.76?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 45 and take away the sum of its digits. What do you get?
  13. 13.28?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.83?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.55?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 90 and take away the sum of its digits. What do you get?
  17. 17.?056 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 23 and take away the sum of its digits. What do you get?
  19. 19.Take 93 and take away the sum of its digits. What do you get?
  20. 20.Take 91 and take away the sum of its digits. What do you get?
  21. 21.Take 42 and take away the sum of its digits. What do you get?
  22. 22.Take 18 and take away the sum of its digits. What do you get?
  23. 23.Take 28 and take away the sum of its digits. What do you get?
  24. 24.Take 32 and take away the sum of its digits. What do you get?
  25. 25.?24 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.2?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.13?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.36?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.185? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 53 and take away the sum of its digits. What do you get?
  31. 31.?258 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?28 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.813? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 15 and take away the sum of its digits. What do you get?
  35. 35.Take 82 and take away the sum of its digits. What do you get?
  36. 36.Take 98 and take away the sum of its digits. What do you get?
  37. 37.Take 76 and take away the sum of its digits. What do you get?
  38. 38.Take 13 and take away the sum of its digits. What do you get?
  39. 39.Take 39 and take away the sum of its digits. What do you get?
  40. 40.Take 97 and take away the sum of its digits. What do you get?

Answer key

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

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