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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 333 · 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.?467 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.4?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?55 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?960 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.7?77 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 71 and take away the sum of its digits. What do you get?
  7. 7.Take 31 and take away the sum of its digits. What do you get?
  8. 8.Take 36 and take away the sum of its digits. What do you get?
  9. 9.?464 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.1?86 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.226? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.7?01 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 86 and take away the sum of its digits. What do you get?
  14. 14.?501 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 72 and take away the sum of its digits. What do you get?
  16. 16.1?44 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?61 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.5?57 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 24 and take away the sum of its digits. What do you get?
  20. 20.?732 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.13?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 83 and take away the sum of its digits. What do you get?
  23. 23.74? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.794? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.230? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 55 and take away the sum of its digits. What do you get?
  27. 27.?786 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.775? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.476? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?830 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.47?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?305 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?590 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.48?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 84 and take away the sum of its digits. What do you get?
  36. 36.Take 22 and take away the sum of its digits. What do you get?
  37. 37.241? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 20 and take away the sum of its digits. What do you get?
  39. 39.?229 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 35 and take away the sum of its digits. What do you get?

Answer key

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

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