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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 100 · 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 44 and take away the sum of its digits. What do you get?
  2. 2.2?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.68?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.16?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.224? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?620 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.483? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.58? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.5?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.8?08 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 29 and take away the sum of its digits. What do you get?
  12. 12.?465 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 62 and take away the sum of its digits. What do you get?
  14. 14.6?89 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.2?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.6?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.5?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.36?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 73 and take away the sum of its digits. What do you get?
  20. 20.Take 55 and take away the sum of its digits. What do you get?
  21. 21.Take 12 and take away the sum of its digits. What do you get?
  22. 22.185? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?613 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.715? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.730? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 19 and take away the sum of its digits. What do you get?
  27. 27.Take 35 and take away the sum of its digits. What do you get?
  28. 28.550? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.2?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.10?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.844? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 18 and take away the sum of its digits. What do you get?
  33. 33.Take 96 and take away the sum of its digits. What do you get?
  34. 34.Take 54 and take away the sum of its digits. What do you get?
  35. 35.Take 43 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.?008 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?048 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?310 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?086 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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