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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 430 · 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 52 and take away the sum of its digits. What do you get?
  2. 2.493? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 88 and take away the sum of its digits. What do you get?
  4. 4.?915 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?809 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 21 and take away the sum of its digits. What do you get?
  7. 7.787? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.5?15 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.63?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 55 and take away the sum of its digits. What do you get?
  11. 11.Take 51 and take away the sum of its digits. What do you get?
  12. 12.Take 20 and take away the sum of its digits. What do you get?
  13. 13.Take 23 and take away the sum of its digits. What do you get?
  14. 14.1?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.2?45 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?241 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?16 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.8?41 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 58 and take away the sum of its digits. What do you get?
  20. 20.Take 73 and take away the sum of its digits. What do you get?
  21. 21.38?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?790 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 28 and take away the sum of its digits. What do you get?
  24. 24.2?11 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.2?77 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 35 and take away the sum of its digits. What do you get?
  27. 27.Take 94 and take away the sum of its digits. What do you get?
  28. 28.?629 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 83 and take away the sum of its digits. What do you get?
  30. 30.Take 30 and take away the sum of its digits. What do you get?
  31. 31.Take 54 and take away the sum of its digits. What do you get?
  32. 32.Take 41 and take away the sum of its digits. What do you get?
  33. 33.Take 14 and take away the sum of its digits. What do you get?
  34. 34.2?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?305 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.10?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?533 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?100 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.2?14 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.5?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 45
  2. 2
  3. 72
  4. 3
  5. 1
  6. 18
  7. 5
  8. 7
  9. 5
  10. 45
  11. 45
  12. 18
  13. 18
  14. 2
  15. 7
  16. 2
  17. 2
  18. 5
  19. 45
  20. 63
  21. 1
  22. 2
  23. 18
  24. 5
  25. 2
  26. 27
  27. 81
  28. 1
  29. 72
  30. 27
  31. 45
  32. 36
  33. 9
  34. 7
  35. 1
  36. 6
  37. 7
  38. 8
  39. 2
  40. 3

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