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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 210 · 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. 1.252? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.19?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.1?47 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 53 and take away the sum of its digits. What do you get?
  5. 5.Take 20 and take away the sum of its digits. What do you get?
  6. 6.Take 14 and take away the sum of its digits. What do you get?
  7. 7.?032 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.2?75 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?633 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?17 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 13 and take away the sum of its digits. What do you get?
  12. 12.38?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.2?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?592 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.29?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.3?08 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.50? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.5?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.8?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.81?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.34?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 45 and take away the sum of its digits. What do you get?
  23. 23.31?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?57 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.55?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 12 and take away the sum of its digits. What do you get?
  27. 27.?242 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.440? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.77? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 83 and take away the sum of its digits. What do you get?
  31. 31.84?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 86 and take away the sum of its digits. What do you get?
  33. 33.45? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.5?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.23?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?330 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.5?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.17? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.279? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.71? 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. 7
  3. 6
  4. 45
  5. 18
  6. 9
  7. 4
  8. 4
  9. 6
  10. 1
  11. 9
  12. 7
  13. 6
  14. 2
  15. 5
  16. 7
  17. 4
  18. 5
  19. 5
  20. 3
  21. 6
  22. 36
  23. 1
  24. 6
  25. 3
  26. 9
  27. 1
  28. 1
  29. 4
  30. 72
  31. 6
  32. 72
  33. 9
  34. 6
  35. 5
  36. 3
  37. 4
  38. 1
  39. 9
  40. 1

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