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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 435 · 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. 1.156? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 73 and take away the sum of its digits. What do you get?
  3. 3.Take 49 and take away the sum of its digits. What do you get?
  4. 4.5?89 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?560 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 87 and take away the sum of its digits. What do you get?
  7. 7.Take 66 and take away the sum of its digits. What do you get?
  8. 8.Take 64 and take away the sum of its digits. What do you get?
  9. 9.35?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 99 and take away the sum of its digits. What do you get?
  11. 11.3?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.2?83 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.9?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?336 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.407? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?624 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.29?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.302? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.4?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 61 and take away the sum of its digits. What do you get?
  21. 21.1?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 74 and take away the sum of its digits. What do you get?
  23. 23.Take 65 and take away the sum of its digits. What do you get?
  24. 24.?874 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?172 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 77 and take away the sum of its digits. What do you get?
  27. 27.Take 18 and take away the sum of its digits. What do you get?
  28. 28.?133 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?016 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?282 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.89?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 20 and take away the sum of its digits. What do you get?
  33. 33.Take 95 and take away the sum of its digits. What do you get?
  34. 34.Take 56 and take away the sum of its digits. What do you get?
  35. 35.Take 46 and take away the sum of its digits. What do you get?
  36. 36.Take 35 and take away the sum of its digits. What do you get?
  37. 37.661? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?259 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?908 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.33?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 6
  2. 63
  3. 36
  4. 5
  5. 7
  6. 72
  7. 54
  8. 54
  9. 9
  10. 81
  11. 6
  12. 5
  13. 3
  14. 6
  15. 7
  16. 6
  17. 8
  18. 4
  19. 8
  20. 54
  21. 8
  22. 63
  23. 54
  24. 8
  25. 8
  26. 63
  27. 9
  28. 2
  29. 2
  30. 6
  31. 1
  32. 18
  33. 81
  34. 45
  35. 36
  36. 27
  37. 5
  38. 2
  39. 1
  40. 4

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