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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 99 · 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. 1.3?37 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.13?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 84 and take away the sum of its digits. What do you get?
  4. 4.80? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.23?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.700? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 91 and take away the sum of its digits. What do you get?
  8. 8.710? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.15?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 61 and take away the sum of its digits. What do you get?
  11. 11.47?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 57 and take away the sum of its digits. What do you get?
  13. 13.5?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.10?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 40 and take away the sum of its digits. What do you get?
  16. 16.?903 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?960 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?257 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.7?44 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.50?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 64 and take away the sum of its digits. What do you get?
  22. 22.Take 19 and take away the sum of its digits. What do you get?
  23. 23.Take 53 and take away the sum of its digits. What do you get?
  24. 24.5?68 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?771 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 54 and take away the sum of its digits. What do you get?
  27. 27.258? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?731 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.490? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.38?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 46 and take away the sum of its digits. What do you get?
  32. 32.?967 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.555? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.21?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.3?16 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 51 and take away the sum of its digits. What do you get?
  37. 37.Take 73 and take away the sum of its digits. What do you get?
  38. 38.577? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.4?69 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 58 and take away the sum of its digits. What do you get?

Answer key

  1. 5
  2. 3
  3. 72
  4. 1
  5. 2
  6. 2
  7. 81
  8. 1
  9. 3
  10. 54
  11. 8
  12. 45
  13. 6
  14. 3
  15. 36
  16. 6
  17. 3
  18. 4
  19. 3
  20. 2
  21. 54
  22. 9
  23. 45
  24. 8
  25. 3
  26. 45
  27. 3
  28. 7
  29. 5
  30. 7
  31. 36
  32. 5
  33. 3
  34. 7
  35. 8
  36. 45
  37. 63
  38. 8
  39. 8
  40. 45

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