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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 392 · 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.Take 71 and take away the sum of its digits. What do you get?
  2. 2.70? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 20 and take away the sum of its digits. What do you get?
  4. 4.?487 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.3?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.5?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 66 and take away the sum of its digits. What do you get?
  8. 8.?330 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?101 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?689 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.68?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 48 and take away the sum of its digits. What do you get?
  13. 13.14? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.69?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 81 and take away the sum of its digits. What do you get?
  16. 16.Take 85 and take away the sum of its digits. What do you get?
  17. 17.211? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.74?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 53 and take away the sum of its digits. What do you get?
  20. 20.133? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.7?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?713 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.64?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?889 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 95 and take away the sum of its digits. What do you get?
  26. 26.Take 17 and take away the sum of its digits. What do you get?
  27. 27.Take 82 and take away the sum of its digits. What do you get?
  28. 28.71?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 25 and take away the sum of its digits. What do you get?
  30. 30.Take 49 and take away the sum of its digits. What do you get?
  31. 31.77?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.194? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 29 and take away the sum of its digits. What do you get?
  34. 34.?622 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 91 and take away the sum of its digits. What do you get?
  36. 36.65?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 75 and take away the sum of its digits. What do you get?
  38. 38.?807 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.4?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 37 and take away the sum of its digits. What do you get?

Answer key

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

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