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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 412 · 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.?383 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.79?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 46 and take away the sum of its digits. What do you get?
  4. 4.56?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.326? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 17 and take away the sum of its digits. What do you get?
  7. 7.Take 49 and take away the sum of its digits. What do you get?
  8. 8.?635 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.6?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 28 and take away the sum of its digits. What do you get?
  11. 11.5?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?436 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.472? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.6?78 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.46?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 35 and take away the sum of its digits. What do you get?
  17. 17.?507 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.8?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 38 and take away the sum of its digits. What do you get?
  20. 20.Take 33 and take away the sum of its digits. What do you get?
  21. 21.1?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?122 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.750? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?717 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 86 and take away the sum of its digits. What do you get?
  26. 26.Take 41 and take away the sum of its digits. What do you get?
  27. 27.Take 27 and take away the sum of its digits. What do you get?
  28. 28.17?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.5?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?957 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 71 and take away the sum of its digits. What do you get?
  32. 32.183? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?924 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.89?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 98 and take away the sum of its digits. What do you get?
  36. 36.Take 11 and take away the sum of its digits. What do you get?
  37. 37.Take 42 and take away the sum of its digits. What do you get?
  38. 38.4?94 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 37 and take away the sum of its digits. What do you get?
  40. 40.?987 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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