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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 874 · 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.?653 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.2?15 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 90 and take away the sum of its digits. What do you get?
  5. 5.71?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?520 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 31 and take away the sum of its digits. What do you get?
  8. 8.8?33 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?346 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 88 and take away the sum of its digits. What do you get?
  12. 12.Take 86 and take away the sum of its digits. What do you get?
  13. 13.Take 17 and take away the sum of its digits. What do you get?
  14. 14.6?27 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 66 and take away the sum of its digits. What do you get?
  16. 16.807? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.19?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 22 and take away the sum of its digits. What do you get?
  20. 20.52?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 33 and take away the sum of its digits. What do you get?
  22. 22.7?48 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.13?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?026 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 93 and take away the sum of its digits. What do you get?
  26. 26.Take 43 and take away the sum of its digits. What do you get?
  27. 27.815? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?75 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.73?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.177? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.22?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.5?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 98 and take away the sum of its digits. What do you get?
  34. 34.46?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 18 and take away the sum of its digits. What do you get?
  36. 36.Take 64 and take away the sum of its digits. What do you get?
  37. 37.2?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.748? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.632? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?563 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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