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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 603 · 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.?032 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.11? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.44?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.604? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 85 and take away the sum of its digits. What do you get?
  6. 6.?005 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 49 and take away the sum of its digits. What do you get?
  8. 8.267? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?361 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.37? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?309 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 99 and take away the sum of its digits. What do you get?
  13. 13.?177 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 95 and take away the sum of its digits. What do you get?
  15. 15.8?28 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.36?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 20 and take away the sum of its digits. What do you get?
  18. 18.Take 39 and take away the sum of its digits. What do you get?
  19. 19.Take 88 and take away the sum of its digits. What do you get?
  20. 20.6?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.36?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 16 and take away the sum of its digits. What do you get?
  23. 23.Take 42 and take away the sum of its digits. What do you get?
  24. 24.459? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 80 and take away the sum of its digits. What do you get?
  26. 26.Take 91 and take away the sum of its digits. What do you get?
  27. 27.1?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.67?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 94 and take away the sum of its digits. What do you get?
  30. 30.?121 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?013 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.58?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.408? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?604 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?805 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.25?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 21 and take away the sum of its digits. What do you get?
  39. 39.?662 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.471? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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