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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 37 · 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 11 and take away the sum of its digits. What do you get?
  2. 2.?310 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.39? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 63 and take away the sum of its digits. What do you get?
  5. 5.?521 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?934 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.708? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 58 and take away the sum of its digits. What do you get?
  9. 9.171? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 81 and take away the sum of its digits. What do you get?
  11. 11.Take 13 and take away the sum of its digits. What do you get?
  12. 12.?049 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.6?01 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.440? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.2?32 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 24 and take away the sum of its digits. What do you get?
  17. 17.3?35 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 38 and take away the sum of its digits. What do you get?
  19. 19.Take 87 and take away the sum of its digits. What do you get?
  20. 20.Take 45 and take away the sum of its digits. What do you get?
  21. 21.Take 65 and take away the sum of its digits. What do you get?
  22. 22.487? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.77?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.4?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.32?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.40?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 54 and take away the sum of its digits. What do you get?
  28. 28.Take 75 and take away the sum of its digits. What do you get?
  29. 29.Take 98 and take away the sum of its digits. What do you get?
  30. 30.6?22 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?308 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.7?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?443 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.325? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.2?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 47 and take away the sum of its digits. What do you get?
  37. 37.Take 64 and take away the sum of its digits. What do you get?
  38. 38.Take 51 and take away the sum of its digits. What do you get?
  39. 39.Take 93 and take away the sum of its digits. What do you get?
  40. 40.59?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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