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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 496 · 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. 1.92? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.25?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.56? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 85 and take away the sum of its digits. What do you get?
  5. 5.Take 22 and take away the sum of its digits. What do you get?
  6. 6.Take 99 and take away the sum of its digits. What do you get?
  7. 7.Take 86 and take away the sum of its digits. What do you get?
  8. 8.Take 31 and take away the sum of its digits. What do you get?
  9. 9.?890 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 13 and take away the sum of its digits. What do you get?
  11. 11.41?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.57? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.7?37 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.4?35 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.87? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 15 and take away the sum of its digits. What do you get?
  17. 17.Take 28 and take away the sum of its digits. What do you get?
  18. 18.Take 46 and take away the sum of its digits. What do you get?
  19. 19.52? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.36?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 35 and take away the sum of its digits. What do you get?
  22. 22.63?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.9?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?291 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.20?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 52 and take away the sum of its digits. What do you get?
  28. 28.15?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.12?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.19?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 33 and take away the sum of its digits. What do you get?
  32. 32.Take 91 and take away the sum of its digits. What do you get?
  33. 33.135? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.80?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 11 and take away the sum of its digits. What do you get?
  36. 36.Take 80 and take away the sum of its digits. What do you get?
  37. 37.Take 36 and take away the sum of its digits. What do you get?
  38. 38.5?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.7?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.6?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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