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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 448 · 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.?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.463? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?157 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.1?52 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?287 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?384 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?98 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?430 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 40 and take away the sum of its digits. What do you get?
  10. 10.?460 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.1?49 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.19?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.824? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.30?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.5?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.1?54 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.9?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.3?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?049 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 78 and take away the sum of its digits. What do you get?
  21. 21.4?74 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 25 and take away the sum of its digits. What do you get?
  23. 23.1?43 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 19 and take away the sum of its digits. What do you get?
  25. 25.826? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 51 and take away the sum of its digits. What do you get?
  27. 27.848? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.297? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 93 and take away the sum of its digits. What do you get?
  30. 30.1?08 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 30 and take away the sum of its digits. What do you get?
  32. 32.?920 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 34 and take away the sum of its digits. What do you get?
  34. 34.6?71 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?524 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.87?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.58?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 18 and take away the sum of its digits. What do you get?
  39. 39.Take 29 and take away the sum of its digits. What do you get?
  40. 40.1?26 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. 5
  3. 5
  4. 1
  5. 1
  6. 3
  7. 1
  8. 2
  9. 36
  10. 8
  11. 4
  12. 4
  13. 4
  14. 7
  15. 6
  16. 8
  17. 9
  18. 2
  19. 5
  20. 63
  21. 3
  22. 18
  23. 1
  24. 9
  25. 2
  26. 45
  27. 7
  28. 9
  29. 81
  30. 9
  31. 27
  32. 7
  33. 27
  34. 4
  35. 7
  36. 2
  37. 7
  38. 9
  39. 18
  40. 9

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