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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 398 · 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. 1.4?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.2?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 62 and take away the sum of its digits. What do you get?
  4. 4.Take 46 and take away the sum of its digits. What do you get?
  5. 5.Take 33 and take away the sum of its digits. What do you get?
  6. 6.Take 43 and take away the sum of its digits. What do you get?
  7. 7.?197 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 60 and take away the sum of its digits. What do you get?
  9. 9.30? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.205? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 35 and take away the sum of its digits. What do you get?
  12. 12.Take 41 and take away the sum of its digits. What do you get?
  13. 13.167? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.427? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?816 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.7?95 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 11 and take away the sum of its digits. What do you get?
  18. 18.111? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?392 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.30?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?49 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 99 and take away the sum of its digits. What do you get?
  23. 23.Take 75 and take away the sum of its digits. What do you get?
  24. 24.Take 51 and take away the sum of its digits. What do you get?
  25. 25.71? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 12 and take away the sum of its digits. What do you get?
  27. 27.?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 40 and take away the sum of its digits. What do you get?
  29. 29.Take 72 and take away the sum of its digits. What do you get?
  30. 30.Take 77 and take away the sum of its digits. What do you get?
  31. 31.171? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.59?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.6?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?086 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.83?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.768? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.65?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 79 and take away the sum of its digits. What do you get?
  39. 39.Take 14 and take away the sum of its digits. What do you get?
  40. 40.Take 28 and take away the sum of its digits. What do you get?

Answer key

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

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