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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 472 · 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.?554 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?679 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 84 and take away the sum of its digits. What do you get?
  4. 4.Take 11 and take away the sum of its digits. What do you get?
  5. 5.Take 41 and take away the sum of its digits. What do you get?
  6. 6.13?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.189? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?974 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 29 and take away the sum of its digits. What do you get?
  10. 10.?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 89 and take away the sum of its digits. What do you get?
  12. 12.?718 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?008 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 68 and take away the sum of its digits. What do you get?
  15. 15.?215 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.7?23 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 13 and take away the sum of its digits. What do you get?
  18. 18.4?14 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?831 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 85 and take away the sum of its digits. What do you get?
  21. 21.Take 66 and take away the sum of its digits. What do you get?
  22. 22.50?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 99 and take away the sum of its digits. What do you get?
  24. 24.Take 57 and take away the sum of its digits. What do you get?
  25. 25.Take 31 and take away the sum of its digits. What do you get?
  26. 26.?673 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.2?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.7?01 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.37? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 15 and take away the sum of its digits. What do you get?
  31. 31.378? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.824? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.40?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 92 and take away the sum of its digits. What do you get?
  35. 35.?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?709 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.7?48 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.454? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.2?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?588 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 4
  2. 5
  3. 72
  4. 9
  5. 36
  6. 2
  7. 9
  8. 7
  9. 18
  10. 9
  11. 72
  12. 2
  13. 1
  14. 54
  15. 1
  16. 6
  17. 9
  18. 9
  19. 6
  20. 72
  21. 54
  22. 4
  23. 81
  24. 45
  25. 27
  26. 2
  27. 6
  28. 1
  29. 8
  30. 9
  31. 9
  32. 4
  33. 1
  34. 81
  35. 8
  36. 2
  37. 8
  38. 5
  39. 5
  40. 6

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