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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 145 · 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. 1.20?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.?876 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 56 and take away the sum of its digits. What do you get?
  4. 4.150? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 69 and take away the sum of its digits. What do you get?
  6. 6.394? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 54 and take away the sum of its digits. What do you get?
  8. 8.Take 67 and take away the sum of its digits. What do you get?
  9. 9.?190 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 34 and take away the sum of its digits. What do you get?
  11. 11.?560 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.494? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.345? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 60 and take away the sum of its digits. What do you get?
  15. 15.Take 95 and take away the sum of its digits. What do you get?
  16. 16.?82 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.10?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?645 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.850? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 32 and take away the sum of its digits. What do you get?
  21. 21.Take 37 and take away the sum of its digits. What do you get?
  22. 22.2?11 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 35 and take away the sum of its digits. What do you get?
  24. 24.?817 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.7?61 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 92 and take away the sum of its digits. What do you get?
  27. 27.Take 70 and take away the sum of its digits. What do you get?
  28. 28.?772 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.5?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 63 and take away the sum of its digits. What do you get?
  31. 31.Take 87 and take away the sum of its digits. What do you get?
  32. 32.3?58 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.52?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 73 and take away the sum of its digits. What do you get?
  35. 35.59?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.23?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.3?97 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?19 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.8?43 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 89 and take away the sum of its digits. What do you get?

Answer key

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

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