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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 655 · 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. 1.792? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?52 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.83?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 95 and take away the sum of its digits. What do you get?
  5. 5.?857 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.1?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?39 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.7?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 42 and take away the sum of its digits. What do you get?
  10. 10.878? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.1?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 73 and take away the sum of its digits. What do you get?
  13. 13.?031 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.9?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.7?82 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 62 and take away the sum of its digits. What do you get?
  17. 17.Take 99 and take away the sum of its digits. What do you get?
  18. 18.?512 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.22?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.3?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?040 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?723 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 31 and take away the sum of its digits. What do you get?
  24. 24.Take 15 and take away the sum of its digits. What do you get?
  25. 25.Take 71 and take away the sum of its digits. What do you get?
  26. 26.49?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.323? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.64?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.266? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 83 and take away the sum of its digits. What do you get?
  31. 31.Take 51 and take away the sum of its digits. What do you get?
  32. 32.387? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 41 and take away the sum of its digits. What do you get?
  34. 34.Take 85 and take away the sum of its digits. What do you get?
  35. 35.8?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.51?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?029 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 97 and take away the sum of its digits. What do you get?
  39. 39.Take 93 and take away the sum of its digits. What do you get?
  40. 40.Take 40 and take away the sum of its digits. What do you get?

Answer key

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

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