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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 304 · 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. 1.621? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 24 and take away the sum of its digits. What do you get?
  3. 3.?716 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?328 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 55 and take away the sum of its digits. What do you get?
  6. 6.Take 20 and take away the sum of its digits. What do you get?
  7. 7.62?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.53?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.797? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.67?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 91 and take away the sum of its digits. What do you get?
  12. 12.19?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.7?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 73 and take away the sum of its digits. What do you get?
  15. 15.?510 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 33 and take away the sum of its digits. What do you get?
  17. 17.1?36 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 35 and take away the sum of its digits. What do you get?
  19. 19.7?84 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?706 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.740? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.3?54 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.1?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?521 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?106 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 17 and take away the sum of its digits. What do you get?
  27. 27.?455 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 97 and take away the sum of its digits. What do you get?
  29. 29.26?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?577 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?088 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 22 and take away the sum of its digits. What do you get?
  33. 33.7?01 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 25 and take away the sum of its digits. What do you get?
  35. 35.Take 44 and take away the sum of its digits. What do you get?
  36. 36.?857 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?049 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.5?88 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.19?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.4?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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