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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 172 · 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. 1.4?88 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.47?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.798? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?681 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?444 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.86?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.604? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 34 and take away the sum of its digits. What do you get?
  9. 9.Take 71 and take away the sum of its digits. What do you get?
  10. 10.Take 48 and take away the sum of its digits. What do you get?
  11. 11.Take 75 and take away the sum of its digits. What do you get?
  12. 12.207? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.5?32 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.2?26 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.17?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 55 and take away the sum of its digits. What do you get?
  17. 17.50?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?685 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 93 and take away the sum of its digits. What do you get?
  20. 20.80?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 30 and take away the sum of its digits. What do you get?
  22. 22.Take 98 and take away the sum of its digits. What do you get?
  23. 23.?142 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.439? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.8?06 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.59? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.3?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.106? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 79 and take away the sum of its digits. What do you get?
  31. 31.3?86 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.5?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?797 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 86 and take away the sum of its digits. What do you get?
  35. 35.2?78 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.36?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.1?94 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.447? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.6?71 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 62 and take away the sum of its digits. What do you get?

Answer key

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

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