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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 204 · 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 13 and take away the sum of its digits. What do you get?
  2. 2.9?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.87?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 35 and take away the sum of its digits. What do you get?
  5. 5.Take 34 and take away the sum of its digits. What do you get?
  6. 6.?433 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.82?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 14 and take away the sum of its digits. What do you get?
  9. 9.Take 55 and take away the sum of its digits. What do you get?
  10. 10.Take 24 and take away the sum of its digits. What do you get?
  11. 11.Take 87 and take away the sum of its digits. What do you get?
  12. 12.487? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 28 and take away the sum of its digits. What do you get?
  14. 14.2?92 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?078 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 22 and take away the sum of its digits. What do you get?
  17. 17.?030 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?905 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 89 and take away the sum of its digits. What do you get?
  20. 20.737? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?590 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 67 and take away the sum of its digits. What do you get?
  23. 23.3?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.70?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.134? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.54?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 83 and take away the sum of its digits. What do you get?
  28. 28.Take 33 and take away the sum of its digits. What do you get?
  29. 29.30? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 16 and take away the sum of its digits. What do you get?
  31. 31.46?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.55?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.37?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.4?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.5?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?610 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.7?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?098 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 23 and take away the sum of its digits. What do you get?
  40. 40.42?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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