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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 915 · 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.?917 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?769 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.1?68 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.5?76 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.1?19 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.22?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 30 and take away the sum of its digits. What do you get?
  8. 8.?332 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 29 and take away the sum of its digits. What do you get?
  10. 10.317? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 37 and take away the sum of its digits. What do you get?
  12. 12.14?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.81?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.439? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?553 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.76?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.18?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 51 and take away the sum of its digits. What do you get?
  19. 19.Take 42 and take away the sum of its digits. What do you get?
  20. 20.Take 22 and take away the sum of its digits. What do you get?
  21. 21.455? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?604 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.356? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 82 and take away the sum of its digits. What do you get?
  25. 25.Take 69 and take away the sum of its digits. What do you get?
  26. 26.102? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.639? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?811 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.1?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.64?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 60 and take away the sum of its digits. What do you get?
  33. 33.?350 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?062 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.23?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.23?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 63 and take away the sum of its digits. What do you get?
  38. 38.Take 14 and take away the sum of its digits. What do you get?
  39. 39.?025 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?470 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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