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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 77 · 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. 1.823? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.203? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.7?95 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 43 and take away the sum of its digits. What do you get?
  5. 5.Take 99 and take away the sum of its digits. What do you get?
  6. 6.Take 81 and take away the sum of its digits. What do you get?
  7. 7.52? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.9?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.6?77 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 55 and take away the sum of its digits. What do you get?
  12. 12.106? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.48?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 32 and take away the sum of its digits. What do you get?
  15. 15.?023 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?731 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?894 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.33?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?365 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 69 and take away the sum of its digits. What do you get?
  21. 21.4?31 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.139? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.2?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?255 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 20 and take away the sum of its digits. What do you get?
  26. 26.Take 21 and take away the sum of its digits. What do you get?
  27. 27.51?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?521 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.489? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?177 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 19 and take away the sum of its digits. What do you get?
  32. 32.74? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.424? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 45 and take away the sum of its digits. What do you get?
  35. 35.Take 38 and take away the sum of its digits. What do you get?
  36. 36.220? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 51 and take away the sum of its digits. What do you get?
  39. 39.Take 73 and take away the sum of its digits. What do you get?
  40. 40.?780 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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