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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 839 · 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 12 and take away the sum of its digits. What do you get?
  2. 2.?037 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 82 and take away the sum of its digits. What do you get?
  4. 4.Take 42 and take away the sum of its digits. What do you get?
  5. 5.Take 28 and take away the sum of its digits. What do you get?
  6. 6.4?68 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.2?56 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 79 and take away the sum of its digits. What do you get?
  9. 9.?452 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 17 and take away the sum of its digits. What do you get?
  11. 11.6?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.60?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 14 and take away the sum of its digits. What do you get?
  15. 15.593? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 26 and take away the sum of its digits. What do you get?
  17. 17.Take 52 and take away the sum of its digits. What do you get?
  18. 18.Take 62 and take away the sum of its digits. What do you get?
  19. 19.81?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.513? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?141 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 29 and take away the sum of its digits. What do you get?
  23. 23.5?88 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 55 and take away the sum of its digits. What do you get?
  25. 25.?786 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.40?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 56 and take away the sum of its digits. What do you get?
  28. 28.Take 69 and take away the sum of its digits. What do you get?
  29. 29.?709 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.229? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?685 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.455? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?691 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?233 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 63 and take away the sum of its digits. What do you get?
  36. 36.?484 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 77 and take away the sum of its digits. What do you get?
  38. 38.139? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.2?20 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 83 and take away the sum of its digits. What do you get?

Answer key

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

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