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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 364 · 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.Take 58 and take away the sum of its digits. What do you get?
  2. 2.?950 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.2?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?611 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?487 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.840? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.2?36 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.48? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.589? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?075 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?338 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.409? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.788? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.24?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.27?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.13?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 37 and take away the sum of its digits. What do you get?
  18. 18.Take 90 and take away the sum of its digits. What do you get?
  19. 19.Take 92 and take away the sum of its digits. What do you get?
  20. 20.Take 43 and take away the sum of its digits. What do you get?
  21. 21.Take 78 and take away the sum of its digits. What do you get?
  22. 22.Take 83 and take away the sum of its digits. What do you get?
  23. 23.Take 42 and take away the sum of its digits. What do you get?
  24. 24.64?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.7?86 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?350 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 88 and take away the sum of its digits. What do you get?
  28. 28.690? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 32 and take away the sum of its digits. What do you get?
  30. 30.Take 14 and take away the sum of its digits. What do you get?
  31. 31.Take 46 and take away the sum of its digits. What do you get?
  32. 32.Take 18 and take away the sum of its digits. What do you get?
  33. 33.Take 99 and take away the sum of its digits. What do you get?
  34. 34.8?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.4?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 54 and take away the sum of its digits. What do you get?
  37. 37.Take 56 and take away the sum of its digits. What do you get?
  38. 38.7?49 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?635 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 69 and take away the sum of its digits. What do you get?

Answer key

  1. 45
  2. 4
  3. 4
  4. 1
  5. 8
  6. 6
  7. 7
  8. 6
  9. 5
  10. 6
  11. 4
  12. 5
  13. 4
  14. 1
  15. 8
  16. 1
  17. 27
  18. 81
  19. 81
  20. 36
  21. 63
  22. 72
  23. 36
  24. 7
  25. 6
  26. 1
  27. 72
  28. 3
  29. 27
  30. 9
  31. 36
  32. 9
  33. 81
  34. 8
  35. 1
  36. 45
  37. 45
  38. 7
  39. 4
  40. 54

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