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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 523 · 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 33 and take away the sum of its digits. What do you get?
  2. 2.65? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 30 and take away the sum of its digits. What do you get?
  4. 4.?503 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?163 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?624 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.73? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 23 and take away the sum of its digits. What do you get?
  9. 9.5?52 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.5?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 52 and take away the sum of its digits. What do you get?
  12. 12.Take 58 and take away the sum of its digits. What do you get?
  13. 13.Take 56 and take away the sum of its digits. What do you get?
  14. 14.Take 46 and take away the sum of its digits. What do you get?
  15. 15.?721 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 68 and take away the sum of its digits. What do you get?
  17. 17.Take 32 and take away the sum of its digits. What do you get?
  18. 18.Take 98 and take away the sum of its digits. What do you get?
  19. 19.4?64 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?188 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?838 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?318 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 18 and take away the sum of its digits. What do you get?
  24. 24.4?45 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 59 and take away the sum of its digits. What do you get?
  26. 26.Take 42 and take away the sum of its digits. What do you get?
  27. 27.4?37 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.104? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.4?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 11 and take away the sum of its digits. What do you get?
  32. 32.?390 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.848? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 74 and take away the sum of its digits. What do you get?
  35. 35.Take 89 and take away the sum of its digits. What do you get?
  36. 36.Take 83 and take away the sum of its digits. What do you get?
  37. 37.?395 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 31 and take away the sum of its digits. What do you get?
  39. 39.?850 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.560? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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