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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 340 · 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.?860 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.595? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?555 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?652 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.582? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 12 and take away the sum of its digits. What do you get?
  7. 7.8?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?521 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.27? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 28 and take away the sum of its digits. What do you get?
  11. 11.?653 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 30 and take away the sum of its digits. What do you get?
  13. 13.Take 33 and take away the sum of its digits. What do you get?
  14. 14.Take 95 and take away the sum of its digits. What do you get?
  15. 15.Take 48 and take away the sum of its digits. What do you get?
  16. 16.Take 35 and take away the sum of its digits. What do you get?
  17. 17.?280 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 53 and take away the sum of its digits. What do you get?
  19. 19.679? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 26 and take away the sum of its digits. What do you get?
  21. 21.Take 79 and take away the sum of its digits. What do you get?
  22. 22.Take 81 and take away the sum of its digits. What do you get?
  23. 23.Take 22 and take away the sum of its digits. What do you get?
  24. 24.?806 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 97 and take away the sum of its digits. What do you get?
  26. 26.Take 31 and take away the sum of its digits. What do you get?
  27. 27.350? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.27?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.310? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?885 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.40?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 49 and take away the sum of its digits. What do you get?
  34. 34.Take 76 and take away the sum of its digits. What do you get?
  35. 35.?800 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 47 and take away the sum of its digits. What do you get?
  37. 37.?057 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?465 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 29 and take away the sum of its digits. What do you get?
  40. 40.328? 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. 8
  3. 3
  4. 5
  5. 3
  6. 9
  7. 3
  8. 1
  9. 9
  10. 18
  11. 4
  12. 27
  13. 27
  14. 81
  15. 36
  16. 27
  17. 8
  18. 45
  19. 5
  20. 18
  21. 63
  22. 72
  23. 18
  24. 4
  25. 81
  26. 27
  27. 1
  28. 3
  29. 6
  30. 5
  31. 6
  32. 4
  33. 36
  34. 63
  35. 1
  36. 36
  37. 6
  38. 3
  39. 18
  40. 5

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