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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 460 · 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. 1.875? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?420 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.8?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 13 and take away the sum of its digits. What do you get?
  5. 5.71?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.6?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?480 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 50 and take away the sum of its digits. What do you get?
  9. 9.Take 69 and take away the sum of its digits. What do you get?
  10. 10.50? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.24?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 90 and take away the sum of its digits. What do you get?
  13. 13.Take 47 and take away the sum of its digits. What do you get?
  14. 14.?646 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.18?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 87 and take away the sum of its digits. What do you get?
  17. 17.?54 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.8?08 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 74 and take away the sum of its digits. What do you get?
  20. 20.365? 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.?067 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?440 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 60 and take away the sum of its digits. What do you get?
  26. 26.6?67 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 46 and take away the sum of its digits. What do you get?
  28. 28.219? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?836 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.3?67 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?19 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 97 and take away the sum of its digits. What do you get?
  33. 33.Take 80 and take away the sum of its digits. What do you get?
  34. 34.13?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.441? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.767? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?231 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?881 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?120 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 78 and take away the sum of its digits. What do you get?

Answer key

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

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