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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 885 · 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 47 and take away the sum of its digits. What do you get?
  2. 2.?305 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 52 and take away the sum of its digits. What do you get?
  4. 4.74?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?27 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.24?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?53 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 30 and take away the sum of its digits. What do you get?
  9. 9.Take 11 and take away the sum of its digits. What do you get?
  10. 10.4?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 22 and take away the sum of its digits. What do you get?
  12. 12.1?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.3?15 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?381 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.73?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 31 and take away the sum of its digits. What do you get?
  17. 17.?788 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.876? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?230 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 96 and take away the sum of its digits. What do you get?
  21. 21.56?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 37 and take away the sum of its digits. What do you get?
  23. 23.87? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?070 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.60?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 67 and take away the sum of its digits. What do you get?
  27. 27.781? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 32 and take away the sum of its digits. What do you get?
  29. 29.6?22 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.692? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?447 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 63 and take away the sum of its digits. What do you get?
  33. 33.Take 19 and take away the sum of its digits. What do you get?
  34. 34.Take 84 and take away the sum of its digits. What do you get?
  35. 35.488? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.6?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.138? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.1?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?578 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.3?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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