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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 956 · 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 79 and take away the sum of its digits. What do you get?
  2. 2.Take 73 and take away the sum of its digits. What do you get?
  3. 3.3?62 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.70?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.60?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 40 and take away the sum of its digits. What do you get?
  7. 7.8?93 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 97 and take away the sum of its digits. What do you get?
  9. 9.?354 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.13?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 32 and take away the sum of its digits. What do you get?
  12. 12.Take 44 and take away the sum of its digits. What do you get?
  13. 13.?120 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.802? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.580? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 13 and take away the sum of its digits. What do you get?
  17. 17.?589 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?884 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.677? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.307? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.6?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 87 and take away the sum of its digits. What do you get?
  23. 23.Take 18 and take away the sum of its digits. What do you get?
  24. 24.Take 88 and take away the sum of its digits. What do you get?
  25. 25.?466 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 23 and take away the sum of its digits. What do you get?
  27. 27.102? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.70?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.725? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 78 and take away the sum of its digits. What do you get?
  31. 31.104? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.7?57 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.1?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 42 and take away the sum of its digits. What do you get?
  35. 35.3?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 26 and take away the sum of its digits. What do you get?
  37. 37.Take 33 and take away the sum of its digits. What do you get?
  38. 38.Take 43 and take away the sum of its digits. What do you get?
  39. 39.1?64 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 70 and take away the sum of its digits. What do you get?

Answer key

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

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