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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 667 · 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 48 and take away the sum of its digits. What do you get?
  2. 2.Take 85 and take away the sum of its digits. What do you get?
  3. 3.2?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.1?81 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.23?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.183? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.3?74 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.57?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 60 and take away the sum of its digits. What do you get?
  10. 10.44?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 90 and take away the sum of its digits. What do you get?
  12. 12.Take 12 and take away the sum of its digits. What do you get?
  13. 13.608? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?618 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.305? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?340 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.1?22 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?453 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.3?86 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 86 and take away the sum of its digits. What do you get?
  21. 21.?689 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 51 and take away the sum of its digits. What do you get?
  23. 23.Take 47 and take away the sum of its digits. What do you get?
  24. 24.Take 39 and take away the sum of its digits. What do you get?
  25. 25.Take 69 and take away the sum of its digits. What do you get?
  26. 26.72? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.?92 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.7?37 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?073 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?985 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 11 and take away the sum of its digits. What do you get?
  32. 32.49?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?824 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?303 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.5?54 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.753? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.5?28 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 72 and take away the sum of its digits. What do you get?
  39. 39.Take 54 and take away the sum of its digits. What do you get?
  40. 40.Take 81 and take away the sum of its digits. What do you get?

Answer key

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

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