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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 958 · 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 80 and take away the sum of its digits. What do you get?
  2. 2.259? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 79 and take away the sum of its digits. What do you get?
  4. 4.Take 54 and take away the sum of its digits. What do you get?
  5. 5.35?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.9?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.8?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 13 and take away the sum of its digits. What do you get?
  9. 9.2?58 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.842? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.79?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.5?91 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.87?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.42?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 75 and take away the sum of its digits. What do you get?
  16. 16.743? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.112? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 29 and take away the sum of its digits. What do you get?
  19. 19.Take 25 and take away the sum of its digits. What do you get?
  20. 20.Take 42 and take away the sum of its digits. What do you get?
  21. 21.Take 90 and take away the sum of its digits. What do you get?
  22. 22.36?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.74?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.114? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?145 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 12 and take away the sum of its digits. What do you get?
  27. 27.Take 38 and take away the sum of its digits. What do you get?
  28. 28.Take 46 and take away the sum of its digits. What do you get?
  29. 29.?033 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.83?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 58 and take away the sum of its digits. What do you get?
  32. 32.?568 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.473? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.56?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 43 and take away the sum of its digits. What do you get?
  36. 36.38?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 21 and take away the sum of its digits. What do you get?
  38. 38.Take 92 and take away the sum of its digits. What do you get?
  39. 39.72?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?440 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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