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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 844 · 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 82 and take away the sum of its digits. What do you get?
  2. 2.69?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.69?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?752 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 13 and take away the sum of its digits. What do you get?
  6. 6.5?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.8?88 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.84?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?707 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.68?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.80?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?209 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 26 and take away the sum of its digits. What do you get?
  14. 14.?791 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 98 and take away the sum of its digits. What do you get?
  16. 16.57?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.463? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 54 and take away the sum of its digits. What do you get?
  19. 19.23?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?910 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 64 and take away the sum of its digits. What do you get?
  22. 22.?006 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.5?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.49?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?562 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?322 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 28 and take away the sum of its digits. What do you get?
  28. 28.Take 31 and take away the sum of its digits. What do you get?
  29. 29.Take 40 and take away the sum of its digits. What do you get?
  30. 30.Take 95 and take away the sum of its digits. What do you get?
  31. 31.Take 30 and take away the sum of its digits. What do you get?
  32. 32.7?92 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.89?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 20 and take away the sum of its digits. What do you get?
  35. 35.7?16 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.79?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.8?26 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 56 and take away the sum of its digits. What do you get?
  39. 39.?818 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 24 and take away the sum of its digits. What do you get?

Answer key

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

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