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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 903 · 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.?883 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.660? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 14 and take away the sum of its digits. What do you get?
  4. 4.7?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.6?89 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 71 and take away the sum of its digits. What do you get?
  7. 7.Take 40 and take away the sum of its digits. What do you get?
  8. 8.?370 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 90 and take away the sum of its digits. What do you get?
  10. 10.40?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.1?43 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.17? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?268 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.233? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.698? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.94? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.4?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 91 and take away the sum of its digits. What do you get?
  20. 20.266? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 58 and take away the sum of its digits. What do you get?
  22. 22.58?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.571? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 42 and take away the sum of its digits. What do you get?
  25. 25.?821 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?232 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 19 and take away the sum of its digits. What do you get?
  28. 28.33? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.717? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 81 and take away the sum of its digits. What do you get?
  31. 31.Take 98 and take away the sum of its digits. What do you get?
  32. 32.Take 77 and take away the sum of its digits. What do you get?
  33. 33.Take 72 and take away the sum of its digits. What do you get?
  34. 34.?420 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 92 and take away the sum of its digits. What do you get?
  36. 36.?760 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 23 and take away the sum of its digits. What do you get?
  38. 38.Take 54 and take away the sum of its digits. What do you get?
  39. 39.Take 11 and take away the sum of its digits. What do you get?
  40. 40.4?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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