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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 418 · 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.?193 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.6?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?292 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?535 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?232 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?130 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?420 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?789 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 23 and take away the sum of its digits. What do you get?
  10. 10.?137 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.472? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.3?83 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 18 and take away the sum of its digits. What do you get?
  14. 14.Take 15 and take away the sum of its digits. What do you get?
  15. 15.Take 29 and take away the sum of its digits. What do you get?
  16. 16.Take 36 and take away the sum of its digits. What do you get?
  17. 17.45?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 11 and take away the sum of its digits. What do you get?
  19. 19.6?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 88 and take away the sum of its digits. What do you get?
  21. 21.?093 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.788? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.89?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.51? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.4?43 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 34 and take away the sum of its digits. What do you get?
  27. 27.Take 43 and take away the sum of its digits. What do you get?
  28. 28.3?85 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.21?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 80 and take away the sum of its digits. What do you get?
  31. 31.67?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 40 and take away the sum of its digits. What do you get?
  33. 33.?067 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 46 and take away the sum of its digits. What do you get?
  35. 35.41?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 55 and take away the sum of its digits. What do you get?
  37. 37.2?07 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?562 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?014 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 21 and take away the sum of its digits. What do you get?

Answer key

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

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