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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 53 · 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 11 and take away the sum of its digits. What do you get?
  2. 2.Take 94 and take away the sum of its digits. What do you get?
  3. 3.15?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 32 and take away the sum of its digits. What do you get?
  5. 5.?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?965 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 20 and take away the sum of its digits. What do you get?
  8. 8.Take 40 and take away the sum of its digits. What do you get?
  9. 9.Take 97 and take away the sum of its digits. What do you get?
  10. 10.?880 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 63 and take away the sum of its digits. What do you get?
  12. 12.377? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.29?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.478? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.875? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 12 and take away the sum of its digits. What do you get?
  17. 17.3?16 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.56?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.795? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?089 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.510? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?179 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.2?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 66 and take away the sum of its digits. What do you get?
  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 96 and take away the sum of its digits. What do you get?
  27. 27.Take 51 and take away the sum of its digits. What do you get?
  28. 28.Take 25 and take away the sum of its digits. What do you get?
  29. 29.5?78 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 33 and take away the sum of its digits. What do you get?
  31. 31.4?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?203 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.244? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 14 and take away the sum of its digits. What do you get?
  35. 35.Take 19 and take away the sum of its digits. What do you get?
  36. 36.1?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 41 and take away the sum of its digits. What do you get?
  38. 38.Take 68 and take away the sum of its digits. What do you get?
  39. 39.455? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.6?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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