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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 558 · 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.?604 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 12 and take away the sum of its digits. What do you get?
  3. 3.?874 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.72?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 71 and take away the sum of its digits. What do you get?
  6. 6.Take 57 and take away the sum of its digits. What do you get?
  7. 7.128? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.6?84 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.167? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.5?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?447 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.4?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.88?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.639? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?850 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 91 and take away the sum of its digits. What do you get?
  17. 17.?345 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 90 and take away the sum of its digits. What do you get?
  19. 19.Take 47 and take away the sum of its digits. What do you get?
  20. 20.9?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 48 and take away the sum of its digits. What do you get?
  22. 22.Take 19 and take away the sum of its digits. What do you get?
  23. 23.?41 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.4?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.73? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.10?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?854 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 53 and take away the sum of its digits. What do you get?
  29. 29.Take 44 and take away the sum of its digits. What do you get?
  30. 30.79?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.671? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?905 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?019 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.3?44 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.90? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.1?86 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.2?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.1?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.2?09 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.716? 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. 9
  3. 8
  4. 9
  5. 63
  6. 45
  7. 7
  8. 9
  9. 4
  10. 1
  11. 3
  12. 5
  13. 5
  14. 9
  15. 5
  16. 81
  17. 6
  18. 81
  19. 36
  20. 2
  21. 36
  22. 9
  23. 4
  24. 5
  25. 8
  26. 5
  27. 1
  28. 45
  29. 36
  30. 1
  31. 4
  32. 4
  33. 8
  34. 7
  35. 9
  36. 3
  37. 1
  38. 2
  39. 7
  40. 4

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