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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 384 · 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 90 and take away the sum of its digits. What do you get?
  2. 2.Take 71 and take away the sum of its digits. What do you get?
  3. 3.Take 87 and take away the sum of its digits. What do you get?
  4. 4.551? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.18? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.94? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?103 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?345 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?697 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?031 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.7?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 84 and take away the sum of its digits. What do you get?
  13. 13.?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 41 and take away the sum of its digits. What do you get?
  15. 15.620? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?223 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?755 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.2?86 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.3?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.801? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?096 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?823 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 33 and take away the sum of its digits. What do you get?
  24. 24.?749 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.2?26 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.540? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 72 and take away the sum of its digits. What do you get?
  28. 28.Take 92 and take away the sum of its digits. What do you get?
  29. 29.775? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 62 and take away the sum of its digits. What do you get?
  31. 31.?921 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 98 and take away the sum of its digits. What do you get?
  33. 33.Take 93 and take away the sum of its digits. What do you get?
  34. 34.Take 91 and take away the sum of its digits. What do you get?
  35. 35.6?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.67?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?439 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 23 and take away the sum of its digits. What do you get?
  39. 39.?899 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 76 and take away the sum of its digits. What do you get?

Answer key

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

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