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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 897 · 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. 1.514? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 77 and take away the sum of its digits. What do you get?
  3. 3.Take 50 and take away the sum of its digits. What do you get?
  4. 4.?553 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.7?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?44 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?557 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.75?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 12 and take away the sum of its digits. What do you get?
  10. 10.Take 51 and take away the sum of its digits. What do you get?
  11. 11.Take 71 and take away the sum of its digits. What do you get?
  12. 12.Take 24 and take away the sum of its digits. What do you get?
  13. 13.517? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?574 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 29 and take away the sum of its digits. What do you get?
  16. 16.?242 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 31 and take away the sum of its digits. What do you get?
  18. 18.Take 23 and take away the sum of its digits. What do you get?
  19. 19.34?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.2?54 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.48?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.3?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.59?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.29? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.456? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.82?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?635 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 32 and take away the sum of its digits. What do you get?
  29. 29.Take 27 and take away the sum of its digits. What do you get?
  30. 30.63?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.2?77 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.7?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?72 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. 35.35?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.6?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.8?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?731 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 66 and take away the sum of its digits. What do you get?
  40. 40.?062 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. 63
  3. 45
  4. 5
  5. 7
  6. 1
  7. 1
  8. 8
  9. 9
  10. 45
  11. 63
  12. 18
  13. 5
  14. 2
  15. 18
  16. 1
  17. 27
  18. 18
  19. 2
  20. 7
  21. 1
  22. 6
  23. 3
  24. 7
  25. 3
  26. 6
  27. 4
  28. 27
  29. 18
  30. 8
  31. 2
  32. 6
  33. 9
  34. 9
  35. 9
  36. 3
  37. 3
  38. 7
  39. 54
  40. 1

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