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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 477 · 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 53 and take away the sum of its digits. What do you get?
  2. 2.68?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.200? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?812 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.3?17 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 11 and take away the sum of its digits. What do you get?
  7. 7.98? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.2?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 81 and take away the sum of its digits. What do you get?
  10. 10.?320 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 42 and take away the sum of its digits. What do you get?
  12. 12.2?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.778? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.80?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.886? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 22 and take away the sum of its digits. What do you get?
  17. 17.?53 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?931 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.2?78 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.497? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 55 and take away the sum of its digits. What do you get?
  22. 22.?105 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 61 and take away the sum of its digits. What do you get?
  24. 24.7?94 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 17 and take away the sum of its digits. What do you get?
  26. 26.Take 50 and take away the sum of its digits. What do you get?
  27. 27.Take 15 and take away the sum of its digits. What do you get?
  28. 28.Take 34 and take away the sum of its digits. What do you get?
  29. 29.9?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 37 and take away the sum of its digits. What do you get?
  31. 31.5?24 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.23?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 35 and take away the sum of its digits. What do you get?
  34. 34.Take 47 and take away the sum of its digits. What do you get?
  35. 35.121? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?312 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 86 and take away the sum of its digits. What do you get?
  38. 38.23?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 14 and take away the sum of its digits. What do you get?
  40. 40.Take 84 and take away the sum of its digits. What do you get?

Answer key

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

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