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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 393 · 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.?285 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 90 and take away the sum of its digits. What do you get?
  3. 3.155? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.703? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 48 and take away the sum of its digits. What do you get?
  6. 6.2?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?098 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.44?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.25?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.14?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.27?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 14 and take away the sum of its digits. What do you get?
  13. 13.Take 92 and take away the sum of its digits. What do you get?
  14. 14.58? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.649? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?421 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 17 and take away the sum of its digits. What do you get?
  18. 18.Take 11 and take away the sum of its digits. What do you get?
  19. 19.315? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 16 and take away the sum of its digits. What do you get?
  21. 21.Take 30 and take away the sum of its digits. What do you get?
  22. 22.?058 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.800? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.149? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?01 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?458 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.696? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?132 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.374? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 27 and take away the sum of its digits. What do you get?
  31. 31.?651 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.84?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.443? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.57?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.55?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.16?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?529 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.4?43 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?452 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.20?3 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. 81
  3. 7
  4. 8
  5. 36
  6. 1
  7. 1
  8. 4
  9. 9
  10. 1
  11. 9
  12. 9
  13. 81
  14. 5
  15. 8
  16. 2
  17. 9
  18. 9
  19. 9
  20. 9
  21. 27
  22. 5
  23. 1
  24. 4
  25. 8
  26. 1
  27. 6
  28. 3
  29. 4
  30. 18
  31. 6
  32. 3
  33. 7
  34. 6
  35. 8
  36. 6
  37. 2
  38. 7
  39. 7
  40. 4

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