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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 387 · 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.?722 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.533? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.792? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?386 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.1?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 55 and take away the sum of its digits. What do you get?
  7. 7.?485 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.3?71 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 29 and take away the sum of its digits. What do you get?
  10. 10.596? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 79 and take away the sum of its digits. What do you get?
  12. 12.?103 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?451 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.5?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.66?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.2?95 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.164? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 85 and take away the sum of its digits. What do you get?
  19. 19.Take 96 and take away the sum of its digits. What do you get?
  20. 20.7?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.6?84 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.89? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?536 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 14 and take away the sum of its digits. What do you get?
  25. 25.Take 19 and take away the sum of its digits. What do you get?
  26. 26.72? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?085 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.5?01 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.3?70 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.55?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 81 and take away the sum of its digits. What do you get?
  32. 32.Take 42 and take away the sum of its digits. What do you get?
  33. 33.?075 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 91 and take away the sum of its digits. What do you get?
  35. 35.5?18 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?789 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?467 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 40 and take away the sum of its digits. What do you get?
  39. 39.3?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 7
  2. 7
  3. 9
  4. 1
  5. 4
  6. 45
  7. 1
  8. 7
  9. 18
  10. 7
  11. 63
  12. 5
  13. 8
  14. 1
  15. 9
  16. 2
  17. 7
  18. 72
  19. 81
  20. 4
  21. 9
  22. 1
  23. 4
  24. 9
  25. 9
  26. 9
  27. 5
  28. 3
  29. 8
  30. 3
  31. 72
  32. 36
  33. 6
  34. 81
  35. 4
  36. 3
  37. 1
  38. 36
  39. 4
  40. 1

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