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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 13 · 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.Take 22 and take away the sum of its digits. What do you get?
  2. 2.8?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?78 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.42?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 71 and take away the sum of its digits. What do you get?
  6. 6.?551 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.101? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.8?24 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?199 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?790 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.8?32 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?941 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 15 and take away the sum of its digits. What do you get?
  14. 14.?505 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.4?41 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.6?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.7?86 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.196? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.3?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.503? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 29 and take away the sum of its digits. What do you get?
  22. 22.?982 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?044 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 63 and take away the sum of its digits. What do you get?
  26. 26.Take 94 and take away the sum of its digits. What do you get?
  27. 27.?850 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.7?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.84? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 38 and take away the sum of its digits. What do you get?
  31. 31.Take 74 and take away the sum of its digits. What do you get?
  32. 32.302? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?637 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.6?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 69 and take away the sum of its digits. What do you get?
  38. 38.Take 41 and take away the sum of its digits. What do you get?
  39. 39.Take 51 and take away the sum of its digits. What do you get?
  40. 40.46?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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