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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 154 · 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. 1.51?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?362 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 27 and take away the sum of its digits. What do you get?
  4. 4.Take 59 and take away the sum of its digits. What do you get?
  5. 5.Take 55 and take away the sum of its digits. What do you get?
  6. 6.Take 17 and take away the sum of its digits. What do you get?
  7. 7.Take 90 and take away the sum of its digits. What do you get?
  8. 8.1?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?390 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.617? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 74 and take away the sum of its digits. What do you get?
  12. 12.Take 87 and take away the sum of its digits. What do you get?
  13. 13.175? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 83 and take away the sum of its digits. What do you get?
  15. 15.Take 86 and take away the sum of its digits. What do you get?
  16. 16.66?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?27 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?301 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?974 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.36?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.6?28 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.610? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 33 and take away the sum of its digits. What do you get?
  26. 26.346? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.375? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?865 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.243? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?069 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.35?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 57 and take away the sum of its digits. What do you get?
  33. 33.2?65 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. 35.5?69 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 45 and take away the sum of its digits. What do you get?
  37. 37.?367 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?838 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?908 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.18?2 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. 7
  3. 18
  4. 45
  5. 45
  6. 9
  7. 81
  8. 1
  9. 6
  10. 4
  11. 63
  12. 72
  13. 5
  14. 72
  15. 72
  16. 1
  17. 9
  18. 5
  19. 7
  20. 8
  21. 2
  22. 2
  23. 7
  24. 9
  25. 27
  26. 5
  27. 3
  28. 8
  29. 9
  30. 3
  31. 8
  32. 45
  33. 5
  34. 9
  35. 7
  36. 36
  37. 2
  38. 8
  39. 1
  40. 7

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