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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 949 · 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.?880 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 27 and take away the sum of its digits. What do you get?
  3. 3.18? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.78?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.180? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.366? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.78?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 41 and take away the sum of its digits. What do you get?
  9. 9.3?76 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 12 and take away the sum of its digits. What do you get?
  11. 11.26?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.178? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.76?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.1?75 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 79 and take away the sum of its digits. What do you get?
  16. 16.Take 18 and take away the sum of its digits. What do you get?
  17. 17.Take 55 and take away the sum of its digits. What do you get?
  18. 18.Take 16 and take away the sum of its digits. What do you get?
  19. 19.5?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 85 and take away the sum of its digits. What do you get?
  21. 21.42?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.24?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 65 and take away the sum of its digits. What do you get?
  24. 24.43?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 54 and take away the sum of its digits. What do you get?
  26. 26.Take 70 and take away the sum of its digits. What do you get?
  27. 27.58?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.8?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?254 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 15 and take away the sum of its digits. What do you get?
  31. 31.18?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 26 and take away the sum of its digits. What do you get?
  33. 33.Take 25 and take away the sum of its digits. What do you get?
  34. 34.?069 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.?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 51 and take away the sum of its digits. What do you get?
  38. 38.Take 81 and take away the sum of its digits. What do you get?
  39. 39.Take 23 and take away the sum of its digits. What do you get?
  40. 40.Take 43 and take away the sum of its digits. What do you get?

Answer key

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

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