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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 329 · 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.?303 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?505 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.134? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.2?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 72 and take away the sum of its digits. What do you get?
  6. 6.?132 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 28 and take away the sum of its digits. What do you get?
  9. 9.3?24 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.1?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?047 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 85 and take away the sum of its digits. What do you get?
  13. 13.Take 42 and take away the sum of its digits. What do you get?
  14. 14.Take 99 and take away the sum of its digits. What do you get?
  15. 15.?438 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 96 and take away the sum of its digits. What do you get?
  17. 17.269? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.17?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?345 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.85?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?425 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?020 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 88 and take away the sum of its digits. What do you get?
  24. 24.Take 40 and take away the sum of its digits. What do you get?
  25. 25.7?84 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?923 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 36 and take away the sum of its digits. What do you get?
  28. 28.735? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?889 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.7?74 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 15 and take away the sum of its digits. What do you get?
  32. 32.40?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.2?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 35 and take away the sum of its digits. What do you get?
  36. 36.329? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 19 and take away the sum of its digits. What do you get?
  38. 38.29?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 31 and take away the sum of its digits. What do you get?
  40. 40.12?6 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. 8
  3. 1
  4. 1
  5. 63
  6. 3
  7. 4
  8. 18
  9. 9
  10. 8
  11. 7
  12. 72
  13. 36
  14. 81
  15. 3
  16. 81
  17. 1
  18. 7
  19. 6
  20. 2
  21. 7
  22. 7
  23. 72
  24. 36
  25. 8
  26. 4
  27. 27
  28. 3
  29. 2
  30. 9
  31. 9
  32. 8
  33. 1
  34. 5
  35. 27
  36. 4
  37. 9
  38. 7
  39. 27
  40. 9

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