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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 651 · 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 70 and take away the sum of its digits. What do you get?
  2. 2.843? 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.Take 36 and take away the sum of its digits. What do you get?
  5. 5.?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.47?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?764 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 87 and take away the sum of its digits. What do you get?
  9. 9.Take 14 and take away the sum of its digits. What do you get?
  10. 10.483? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.2?69 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 52 and take away the sum of its digits. What do you get?
  13. 13.Take 31 and take away the sum of its digits. What do you get?
  14. 14.66?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 35 and take away the sum of its digits. What do you get?
  16. 16.?814 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 25 and take away the sum of its digits. What do you get?
  18. 18.37?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.73?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.85?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.55?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.72?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 94 and take away the sum of its digits. What do you get?
  24. 24.?798 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.598? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.490? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.79?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?859 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.749? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 77 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.?118 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.884? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?929 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 45 and take away the sum of its digits. What do you get?
  36. 36.Take 79 and take away the sum of its digits. What do you get?
  37. 37.31?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.641? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.100? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 41 and take away the sum of its digits. What do you get?

Answer key

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

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