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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 419 · 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. 1.559? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 58 and take away the sum of its digits. What do you get?
  3. 3.386? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 36 and take away the sum of its digits. What do you get?
  5. 5.?247 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.79?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.85?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.538? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.686? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?494 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 87 and take away the sum of its digits. What do you get?
  12. 12.Take 45 and take away the sum of its digits. What do you get?
  13. 13.87? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.8?58 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.10?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 86 and take away the sum of its digits. What do you get?
  17. 17.424? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.8?74 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.84?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?518 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.52?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.5?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.77? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 31 and take away the sum of its digits. What do you get?
  26. 26.?220 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.34? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 12 and take away the sum of its digits. What do you get?
  29. 29.Take 78 and take away the sum of its digits. What do you get?
  30. 30.3?01 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 20 and take away the sum of its digits. What do you get?
  32. 32.315? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?353 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?883 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.897? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.888? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.24?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.10?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?615 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?964 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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