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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 288 · 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. 1.19?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?974 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 85 and take away the sum of its digits. What do you get?
  4. 4.Take 71 and take away the sum of its digits. What do you get?
  5. 5.224? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 77 and take away the sum of its digits. What do you get?
  7. 7.Take 97 and take away the sum of its digits. What do you get?
  8. 8.37?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.6?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.4?61 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 34 and take away the sum of its digits. What do you get?
  12. 12.?44 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?484 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?215 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.11?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 20 and take away the sum of its digits. What do you get?
  17. 17.?574 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.4?26 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 37 and take away the sum of its digits. What do you get?
  20. 20.314? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 48 and take away the sum of its digits. What do you get?
  22. 22.3?44 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.2?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.63?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.377? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?958 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 56 and take away the sum of its digits. What do you get?
  28. 28.521? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.7?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.8?07 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 35 and take away the sum of its digits. What do you get?
  32. 32.?178 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 46 and take away the sum of its digits. What do you get?
  34. 34.2?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.7?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.671? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 28 and take away the sum of its digits. What do you get?
  38. 38.Take 45 and take away the sum of its digits. What do you get?
  39. 39.345? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.16?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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