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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 942 · 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 79 and take away the sum of its digits. What do you get?
  2. 2.Take 64 and take away the sum of its digits. What do you get?
  3. 3.Take 25 and take away the sum of its digits. What do you get?
  4. 4.?520 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 11 and take away the sum of its digits. What do you get?
  6. 6.57?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?668 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.4?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.437? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 30 and take away the sum of its digits. What do you get?
  11. 11.?357 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?068 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.496? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?775 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?708 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.545? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 67 and take away the sum of its digits. What do you get?
  18. 18.399? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.2?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.13?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 98 and take away the sum of its digits. What do you get?
  22. 22.81?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.869? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?440 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 42 and take away the sum of its digits. What do you get?
  26. 26.?942 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 77 and take away the sum of its digits. What do you get?
  28. 28.43?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 55 and take away the sum of its digits. What do you get?
  30. 30.?167 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?293 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.6?81 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 65 and take away the sum of its digits. What do you get?
  34. 34.5?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 87 and take away the sum of its digits. What do you get?
  36. 36.?040 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.93? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.30?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?661 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 86 and take away the sum of its digits. What do you get?

Answer key

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

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