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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 47 · 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 55 and take away the sum of its digits. What do you get?
  2. 2.Take 28 and take away the sum of its digits. What do you get?
  3. 3.89?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?008 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 40 and take away the sum of its digits. What do you get?
  6. 6.Take 14 and take away the sum of its digits. What do you get?
  7. 7.68?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.302? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 62 and take away the sum of its digits. What do you get?
  10. 10.24?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.867? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.300? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.19?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?078 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.3?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?375 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 54 and take away the sum of its digits. What do you get?
  18. 18.Take 94 and take away the sum of its digits. What do you get?
  19. 19.Take 66 and take away the sum of its digits. What do you get?
  20. 20.5?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.266? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 22 and take away the sum of its digits. What do you get?
  23. 23.23?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.1?19 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 88 and take away the sum of its digits. What do you get?
  26. 26.52?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 29 and take away the sum of its digits. What do you get?
  28. 28.Take 34 and take away the sum of its digits. What do you get?
  29. 29.74?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.81?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?834 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.233? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 19 and take away the sum of its digits. What do you get?
  34. 34.409? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 68 and take away the sum of its digits. What do you get?
  36. 36.Take 49 and take away the sum of its digits. What do you get?
  37. 37.3?67 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.148? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.1?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.23?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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