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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 54 · 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.?829 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.779? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.1?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.5?11 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.21?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.201? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 15 and take away the sum of its digits. What do you get?
  8. 8.Take 34 and take away the sum of its digits. What do you get?
  9. 9.7?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 85 and take away the sum of its digits. What do you get?
  11. 11.5?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.51?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 88 and take away the sum of its digits. What do you get?
  14. 14.Take 22 and take away the sum of its digits. What do you get?
  15. 15.7?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?143 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 67 and take away the sum of its digits. What do you get?
  18. 18.844? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?839 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 89 and take away the sum of its digits. What do you get?
  22. 22.?035 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.1?39 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.19?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.7?45 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 17 and take away the sum of its digits. What do you get?
  27. 27.Take 90 and take away the sum of its digits. What do you get?
  28. 28.114? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.27?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.10? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.7?61 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.414? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.59?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.2?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 52 and take away the sum of its digits. What do you get?
  36. 36.44?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.61?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.11?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?611 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.49?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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