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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 654 · 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. 1.780? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.14?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 26 and take away the sum of its digits. What do you get?
  4. 4.1?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 68 and take away the sum of its digits. What do you get?
  6. 6.?912 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?246 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 80 and take away the sum of its digits. What do you get?
  9. 9.88?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?389 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.8?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.1?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?332 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.10?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.501? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 59 and take away the sum of its digits. What do you get?
  17. 17.745? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 15 and take away the sum of its digits. What do you get?
  19. 19.31?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 79 and take away the sum of its digits. What do you get?
  21. 21.Take 78 and take away the sum of its digits. What do you get?
  22. 22.129? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?19 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 94 and take away the sum of its digits. What do you get?
  26. 26.278? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.8?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 11 and take away the sum of its digits. What do you get?
  29. 29.Take 30 and take away the sum of its digits. What do you get?
  30. 30.Take 20 and take away the sum of its digits. What do you get?
  31. 31.Take 45 and take away the sum of its digits. What do you get?
  32. 32.Take 55 and take away the sum of its digits. What do you get?
  33. 33.73?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.4?54 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.76? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.5?88 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.8?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?501 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.75?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.18?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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