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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 930 · 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. 1.4?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 88 and take away the sum of its digits. What do you get?
  3. 3.Take 97 and take away the sum of its digits. What do you get?
  4. 4.Take 39 and take away the sum of its digits. What do you get?
  5. 5.5?37 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?878 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 32 and take away the sum of its digits. What do you get?
  8. 8.?853 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.5?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 26 and take away the sum of its digits. What do you get?
  11. 11.Take 82 and take away the sum of its digits. What do you get?
  12. 12.?782 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.890? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?395 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 52 and take away the sum of its digits. What do you get?
  16. 16.?239 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?030 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 13 and take away the sum of its digits. What do you get?
  19. 19.?389 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 16 and take away the sum of its digits. What do you get?
  21. 21.62?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 29 and take away the sum of its digits. What do you get?
  23. 23.Take 48 and take away the sum of its digits. What do you get?
  24. 24.?446 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.4?22 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?014 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.82?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?107 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?788 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.1?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 55 and take away the sum of its digits. What do you get?
  33. 33.Take 90 and take away the sum of its digits. What do you get?
  34. 34.262? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 93 and take away the sum of its digits. What do you get?
  36. 36.Take 65 and take away the sum of its digits. What do you get?
  37. 37.Take 60 and take away the sum of its digits. What do you get?
  38. 38.715? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 87 and take away the sum of its digits. What do you get?
  40. 40.Take 73 and take away the sum of its digits. What do you get?

Answer key

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

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