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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 42 · 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. 1.23? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 42 and take away the sum of its digits. What do you get?
  3. 3.883? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.17?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.743? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 23 and take away the sum of its digits. What do you get?
  7. 7.?130 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 26 and take away the sum of its digits. What do you get?
  9. 9.Take 92 and take away the sum of its digits. What do you get?
  10. 10.91? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 93 and take away the sum of its digits. What do you get?
  12. 12.510? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.229? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.263? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 94 and take away the sum of its digits. What do you get?
  16. 16.?034 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 61 and take away the sum of its digits. What do you get?
  18. 18.516? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.211? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.72?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 73 and take away the sum of its digits. What do you get?
  22. 22.Take 72 and take away the sum of its digits. What do you get?
  23. 23.?969 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.55?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 24 and take away the sum of its digits. What do you get?
  26. 26.?62 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 45 and take away the sum of its digits. What do you get?
  28. 28.Take 43 and take away the sum of its digits. What do you get?
  29. 29.?293 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?955 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.389? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 27 and take away the sum of its digits. What do you get?
  33. 33.2?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.51?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.7?74 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.10?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 66 and take away the sum of its digits. What do you get?
  38. 38.Take 46 and take away the sum of its digits. What do you get?
  39. 39.2?95 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?053 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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