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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 486 · 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 87 and take away the sum of its digits. What do you get?
  2. 2.?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?381 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.6?24 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 89 and take away the sum of its digits. What do you get?
  6. 6.Take 73 and take away the sum of its digits. What do you get?
  7. 7.Take 55 and take away the sum of its digits. What do you get?
  8. 8.213? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 67 and take away the sum of its digits. What do you get?
  10. 10.Take 14 and take away the sum of its digits. What do you get?
  11. 11.Take 80 and take away the sum of its digits. What do you get?
  12. 12.Take 38 and take away the sum of its digits. What do you get?
  13. 13.Take 29 and take away the sum of its digits. What do you get?
  14. 14.206? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?54 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 34 and take away the sum of its digits. What do you get?
  17. 17.796? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.50?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.7?64 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.2?86 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.2?98 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?007 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.1?16 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.3?32 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.7?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.1?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?929 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.3?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.2?29 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?406 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.70?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.390? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.5?01 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.422? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?692 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?583 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.19?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 39 and take away the sum of its digits. What do you get?
  39. 39.289? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.4?65 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. 9
  3. 6
  4. 6
  5. 72
  6. 63
  7. 45
  8. 3
  9. 54
  10. 9
  11. 72
  12. 27
  13. 18
  14. 1
  15. 9
  16. 27
  17. 5
  18. 3
  19. 1
  20. 2
  21. 8
  22. 2
  23. 1
  24. 1
  25. 9
  26. 2
  27. 7
  28. 9
  29. 5
  30. 8
  31. 7
  32. 6
  33. 3
  34. 1
  35. 1
  36. 2
  37. 3
  38. 27
  39. 8
  40. 3

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