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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 574 · 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. 1.96? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 23 and take away the sum of its digits. What do you get?
  3. 3.Take 11 and take away the sum of its digits. What do you get?
  4. 4.830? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.54?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 68 and take away the sum of its digits. What do you get?
  7. 7.Take 89 and take away the sum of its digits. What do you get?
  8. 8.Take 65 and take away the sum of its digits. What do you get?
  9. 9.Take 87 and take away the sum of its digits. What do you get?
  10. 10.?635 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?031 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 70 and take away the sum of its digits. What do you get?
  13. 13.?048 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.11?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 56 and take away the sum of its digits. What do you get?
  16. 16.Take 37 and take away the sum of its digits. What do you get?
  17. 17.?489 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.66?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?578 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.556? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?168 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 35 and take away the sum of its digits. What do you get?
  23. 23.Take 81 and take away the sum of its digits. What do you get?
  24. 24.66? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 83 and take away the sum of its digits. What do you get?
  26. 26.845? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.178? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.88?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 18 and take away the sum of its digits. What do you get?
  30. 30.475? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 21 and take away the sum of its digits. What do you get?
  32. 32.66?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 29 and take away the sum of its digits. What do you get?
  34. 34.7?69 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.278? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 52 and take away the sum of its digits. What do you get?
  37. 37.2?42 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 60 and take away the sum of its digits. What do you get?
  39. 39.6?83 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.6?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 3
  2. 18
  3. 9
  4. 7
  5. 5
  6. 54
  7. 72
  8. 54
  9. 72
  10. 4
  11. 5
  12. 63
  13. 6
  14. 9
  15. 45
  16. 27
  17. 6
  18. 2
  19. 7
  20. 2
  21. 3
  22. 27
  23. 72
  24. 6
  25. 72
  26. 1
  27. 2
  28. 7
  29. 9
  30. 2
  31. 18
  32. 6
  33. 18
  34. 5
  35. 1
  36. 45
  37. 1
  38. 54
  39. 1
  40. 5

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