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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 298 · 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.?226 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.5?39 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.5?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 12 and take away the sum of its digits. What do you get?
  5. 5.?508 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.67?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.7?64 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?931 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.266? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.5?53 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 24 and take away the sum of its digits. What do you get?
  12. 12.79?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.39?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?818 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.75?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 22 and take away the sum of its digits. What do you get?
  17. 17.Take 11 and take away the sum of its digits. What do you get?
  18. 18.Take 32 and take away the sum of its digits. What do you get?
  19. 19.49?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.84?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.65?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 34 and take away the sum of its digits. What do you get?
  23. 23.?952 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?561 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 97 and take away the sum of its digits. What do you get?
  26. 26.499? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.689? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 65 and take away the sum of its digits. What do you get?
  29. 29.Take 55 and take away the sum of its digits. What do you get?
  30. 30.8?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?91 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 73 and take away the sum of its digits. What do you get?
  33. 33.63? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.111? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 48 and take away the sum of its digits. What do you get?
  36. 36.68?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?205 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.5?95 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 15 and take away the sum of its digits. What do you get?
  40. 40.9?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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