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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 3 · 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.?831 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.551? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 11 and take away the sum of its digits. What do you get?
  5. 5.57?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.7?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.131? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?358 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 75 and take away the sum of its digits. What do you get?
  10. 10.88?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.3?99 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 32 and take away the sum of its digits. What do you get?
  13. 13.570? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.7?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.1?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.6?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 74 and take away the sum of its digits. What do you get?
  18. 18.26?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?028 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.691? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 66 and take away the sum of its digits. What do you get?
  22. 22.Take 64 and take away the sum of its digits. What do you get?
  23. 23.Take 53 and take away the sum of its digits. What do you get?
  24. 24.?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 56 and take away the sum of its digits. What do you get?
  26. 26.?883 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 67 and take away the sum of its digits. What do you get?
  28. 28.Take 14 and take away the sum of its digits. What do you get?
  29. 29.812? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 48 and take away the sum of its digits. What do you get?
  31. 31.Take 70 and take away the sum of its digits. What do you get?
  32. 32.891? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?314 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.3?32 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 51 and take away the sum of its digits. What do you get?
  36. 36.Take 85 and take away the sum of its digits. What do you get?
  37. 37.?15 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?21 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.369? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?476 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. 6
  3. 7
  4. 9
  5. 5
  6. 4
  7. 4
  8. 2
  9. 63
  10. 8
  11. 6
  12. 27
  13. 6
  14. 4
  15. 8
  16. 6
  17. 63
  18. 2
  19. 8
  20. 2
  21. 54
  22. 54
  23. 45
  24. 5
  25. 45
  26. 8
  27. 54
  28. 9
  29. 7
  30. 36
  31. 63
  32. 9
  33. 1
  34. 1
  35. 45
  36. 72
  37. 3
  38. 6
  39. 9
  40. 1

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