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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 917 · 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. 1.67?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?039 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 28 and take away the sum of its digits. What do you get?
  4. 4.?232 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?137 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?075 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 96 and take away the sum of its digits. What do you get?
  8. 8.1?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?442 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 12 and take away the sum of its digits. What do you get?
  11. 11.346? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 98 and take away the sum of its digits. What do you get?
  13. 13.Take 74 and take away the sum of its digits. What do you get?
  14. 14.?634 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 71 and take away the sum of its digits. What do you get?
  16. 16.25?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?72 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 35 and take away the sum of its digits. What do you get?
  19. 19.Take 56 and take away the sum of its digits. What do you get?
  20. 20.1?89 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 16 and take away the sum of its digits. What do you get?
  22. 22.66?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?493 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?93 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 90 and take away the sum of its digits. What do you get?
  26. 26.464? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.8?78 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?879 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 18 and take away the sum of its digits. What do you get?
  30. 30.Take 81 and take away the sum of its digits. What do you get?
  31. 31.58?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 49 and take away the sum of its digits. What do you get?
  33. 33.30?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.170? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 39 and take away the sum of its digits. What do you get?
  36. 36.140? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.2?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.3?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.46?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?448 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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