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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 234 · 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 72 and take away the sum of its digits. What do you get?
  2. 2.287? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.501? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 25 and take away the sum of its digits. What do you get?
  5. 5.2?16 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 19 and take away the sum of its digits. What do you get?
  7. 7.5?78 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 11 and take away the sum of its digits. What do you get?
  9. 9.16?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.71?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?537 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?789 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.5?22 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.5?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?785 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?142 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.4?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 73 and take away the sum of its digits. What do you get?
  19. 19.?987 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 57 and take away the sum of its digits. What do you get?
  21. 21.761? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.56?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.6?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.6?94 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.207? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 77 and take away the sum of its digits. What do you get?
  27. 27.Take 60 and take away the sum of its digits. What do you get?
  28. 28.71?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 34 and take away the sum of its digits. What do you get?
  30. 30.Take 78 and take away the sum of its digits. What do you get?
  31. 31.?417 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.329? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.80?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?366 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.46? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.467? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.268? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 96 and take away the sum of its digits. What do you get?
  39. 39.7?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?019 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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