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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 510 · 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. 1.4?86 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.726? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?017 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 38 and take away the sum of its digits. What do you get?
  5. 5.?582 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.101? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 17 and take away the sum of its digits. What do you get?
  8. 8.Take 61 and take away the sum of its digits. What do you get?
  9. 9.170? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?571 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?692 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.6?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.52? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.502? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.1?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 84 and take away the sum of its digits. What do you get?
  17. 17.Take 95 and take away the sum of its digits. What do you get?
  18. 18.5?33 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.5?55 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.6?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.7?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 27 and take away the sum of its digits. What do you get?
  23. 23.50?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.639? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.8?28 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.7?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.2?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?32 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.85? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 98 and take away the sum of its digits. What do you get?
  31. 31.Take 26 and take away the sum of its digits. What do you get?
  32. 32.2?64 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.4?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 93 and take away the sum of its digits. What do you get?
  35. 35.?039 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.505? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 76 and take away the sum of its digits. What do you get?
  38. 38.Take 56 and take away the sum of its digits. What do you get?
  39. 39.Take 71 and take away the sum of its digits. What do you get?
  40. 40.33?0 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. 3
  3. 1
  4. 27
  5. 3
  6. 7
  7. 9
  8. 54
  9. 1
  10. 5
  11. 1
  12. 7
  13. 2
  14. 2
  15. 6
  16. 72
  17. 81
  18. 7
  19. 3
  20. 4
  21. 1
  22. 18
  23. 3
  24. 9
  25. 9
  26. 9
  27. 1
  28. 4
  29. 5
  30. 81
  31. 18
  32. 6
  33. 5
  34. 81
  35. 6
  36. 8
  37. 63
  38. 45
  39. 63
  40. 3

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