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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 247 · 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 32 and take away the sum of its digits. What do you get?
  2. 2.?581 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 50 and take away the sum of its digits. What do you get?
  4. 4.162? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.708? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.8?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.36?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 49 and take away the sum of its digits. What do you get?
  9. 9.?640 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?479 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 25 and take away the sum of its digits. What do you get?
  12. 12.6?29 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.757? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 74 and take away the sum of its digits. What do you get?
  15. 15.?007 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 86 and take away the sum of its digits. What do you get?
  17. 17.Take 36 and take away the sum of its digits. What do you get?
  18. 18.688? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.373? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.1?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 33 and take away the sum of its digits. What do you get?
  22. 22.Take 27 and take away the sum of its digits. What do you get?
  23. 23.24?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.196? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 81 and take away the sum of its digits. What do you get?
  26. 26.?269 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 13 and take away the sum of its digits. What do you get?
  28. 28.Take 31 and take away the sum of its digits. What do you get?
  29. 29.Take 72 and take away the sum of its digits. What do you get?
  30. 30.?793 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.115? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 43 and take away the sum of its digits. What do you get?
  33. 33.Take 73 and take away the sum of its digits. What do you get?
  34. 34.62?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.608? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.501? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.3?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 91 and take away the sum of its digits. What do you get?
  39. 39.Take 53 and take away the sum of its digits. What do you get?
  40. 40.16?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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