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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 275 · 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. 1.6?77 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.221? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 82 and take away the sum of its digits. What do you get?
  4. 4.Take 63 and take away the sum of its digits. What do you get?
  5. 5.Take 12 and take away the sum of its digits. What do you get?
  6. 6.199? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.511? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?331 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.769? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.813? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.48?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.40?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?295 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?586 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 25 and take away the sum of its digits. What do you get?
  16. 16.Take 32 and take away the sum of its digits. What do you get?
  17. 17.?214 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 75 and take away the sum of its digits. What do you get?
  19. 19.?824 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?08 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.808? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.88?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.80?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 21 and take away the sum of its digits. What do you get?
  25. 25.5?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.5?74 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?177 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?01 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.2?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.62?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.74?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.11?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 60 and take away the sum of its digits. What do you get?
  34. 34.39?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 84 and take away the sum of its digits. What do you get?
  36. 36.Take 78 and take away the sum of its digits. What do you get?
  37. 37.8?39 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 48 and take away the sum of its digits. What do you get?
  39. 39.36?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.76?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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