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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 796 · 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. 1.221? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.1?39 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.505? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.271? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 59 and take away the sum of its digits. What do you get?
  6. 6.Take 49 and take away the sum of its digits. What do you get?
  7. 7.225? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 43 and take away the sum of its digits. What do you get?
  9. 9.Take 28 and take away the sum of its digits. What do you get?
  10. 10.Take 88 and take away the sum of its digits. What do you get?
  11. 11.Take 11 and take away the sum of its digits. What do you get?
  12. 12.?026 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?01 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.65?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 82 and take away the sum of its digits. What do you get?
  16. 16.Take 85 and take away the sum of its digits. What do you get?
  17. 17.Take 54 and take away the sum of its digits. What do you get?
  18. 18.75? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?532 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?547 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.8?92 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 71 and take away the sum of its digits. What do you get?
  23. 23.5?57 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 33 and take away the sum of its digits. What do you get?
  25. 25.1?61 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.7?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 67 and take away the sum of its digits. What do you get?
  28. 28.?380 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 46 and take away the sum of its digits. What do you get?
  30. 30.Take 24 and take away the sum of its digits. What do you get?
  31. 31.?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.321? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.3?76 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 50 and take away the sum of its digits. What do you get?
  35. 35.19?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 15 and take away the sum of its digits. What do you get?
  37. 37.?989 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 98 and take away the sum of its digits. What do you get?
  39. 39.?154 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 34 and take away the sum of its digits. What do you get?

Answer key

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

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