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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 378 · 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.?777 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.507? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 38 and take away the sum of its digits. What do you get?
  4. 4.Take 86 and take away the sum of its digits. What do you get?
  5. 5.?27 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.200? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.483? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 35 and take away the sum of its digits. What do you get?
  10. 10.?030 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.73? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 67 and take away the sum of its digits. What do you get?
  13. 13.Take 64 and take away the sum of its digits. What do you get?
  14. 14.8?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?800 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 80 and take away the sum of its digits. What do you get?
  17. 17.Take 33 and take away the sum of its digits. What do you get?
  18. 18.Take 22 and take away the sum of its digits. What do you get?
  19. 19.Take 51 and take away the sum of its digits. What do you get?
  20. 20.Take 58 and take away the sum of its digits. What do you get?
  21. 21.882? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.5?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?827 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?201 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 61 and take away the sum of its digits. What do you get?
  26. 26.Take 90 and take away the sum of its digits. What do you get?
  27. 27.524? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 39 and take away the sum of its digits. What do you get?
  29. 29.?761 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.9?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?53 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. 33.10?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 27 and take away the sum of its digits. What do you get?
  35. 35.Take 83 and take away the sum of its digits. What do you get?
  36. 36.4?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.227? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.5?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.267? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 11 and take away the sum of its digits. What do you get?

Answer key

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

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