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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 495 · 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. 1.75?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.224? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.21?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.302? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?362 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 75 and take away the sum of its digits. What do you get?
  7. 7.Take 37 and take away the sum of its digits. What do you get?
  8. 8.693? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?151 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.7?45 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?439 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 18 and take away the sum of its digits. What do you get?
  14. 14.116? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 34 and take away the sum of its digits. What do you get?
  16. 16.Take 31 and take away the sum of its digits. What do you get?
  17. 17.2?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.2?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 13 and take away the sum of its digits. What do you get?
  20. 20.Take 57 and take away the sum of its digits. What do you get?
  21. 21.2?43 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 78 and take away the sum of its digits. What do you get?
  23. 23.Take 96 and take away the sum of its digits. What do you get?
  24. 24.Take 72 and take away the sum of its digits. What do you get?
  25. 25.Take 49 and take away the sum of its digits. What do you get?
  26. 26.?940 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 50 and take away the sum of its digits. What do you get?
  28. 28.13?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 51 and take away the sum of its digits. What do you get?
  30. 30.333? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?235 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.6?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.45?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?350 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.40?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.5?59 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.3?22 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?653 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?447 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.474? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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