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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 317 · 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.?051 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 71 and take away the sum of its digits. What do you get?
  4. 4.164? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.39?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 11 and take away the sum of its digits. What do you get?
  7. 7.359? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.44? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.4?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 37 and take away the sum of its digits. What do you get?
  11. 11.Take 62 and take away the sum of its digits. What do you get?
  12. 12.?070 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?890 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.7?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.435? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?75 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?454 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 86 and take away the sum of its digits. What do you get?
  19. 19.355? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.73?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.565? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 18 and take away the sum of its digits. What do you get?
  23. 23.?907 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.34?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 29 and take away the sum of its digits. What do you get?
  26. 26.30? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 53 and take away the sum of its digits. What do you get?
  28. 28.4?17 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?422 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?007 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.380? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 57 and take away the sum of its digits. What do you get?
  33. 33.221? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.330? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 19 and take away the sum of its digits. What do you get?
  36. 36.?608 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.643? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 24 and take away the sum of its digits. What do you get?
  39. 39.Take 36 and take away the sum of its digits. What do you get?
  40. 40.?920 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 3
  2. 63
  3. 63
  4. 7
  5. 9
  6. 9
  7. 1
  8. 1
  9. 2
  10. 27
  11. 54
  12. 2
  13. 1
  14. 2
  15. 6
  16. 6
  17. 5
  18. 72
  19. 5
  20. 4
  21. 2
  22. 9
  23. 2
  24. 6
  25. 18
  26. 6
  27. 45
  28. 6
  29. 1
  30. 2
  31. 7
  32. 45
  33. 4
  34. 3
  35. 9
  36. 4
  37. 5
  38. 18
  39. 27
  40. 7

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