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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 355 · 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.?228 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 63 and take away the sum of its digits. What do you get?
  3. 3.Take 66 and take away the sum of its digits. What do you get?
  4. 4.?757 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 87 and take away the sum of its digits. What do you get?
  6. 6.Take 80 and take away the sum of its digits. What do you get?
  7. 7.445? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 96 and take away the sum of its digits. What do you get?
  9. 9.1?08 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.52?8 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.?070 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 20 and take away the sum of its digits. What do you get?
  14. 14.Take 55 and take away the sum of its digits. What do you get?
  15. 15.33?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.710? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 89 and take away the sum of its digits. What do you get?
  18. 18.Take 44 and take away the sum of its digits. What do you get?
  19. 19.Take 92 and take away the sum of its digits. What do you get?
  20. 20.?617 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 34 and take away the sum of its digits. What do you get?
  22. 22.Take 69 and take away the sum of its digits. What do you get?
  23. 23.425? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.77? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 93 and take away the sum of its digits. What do you get?
  26. 26.3?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.800? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.88?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?187 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.9?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.105? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.51?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?222 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.504? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?888 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?628 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 49 and take away the sum of its digits. What do you get?
  38. 38.81? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.7?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?457 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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