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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 375 · 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 42 and take away the sum of its digits. What do you get?
  2. 2.19?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?067 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.522? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.55?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?005 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 45 and take away the sum of its digits. What do you get?
  8. 8.Take 96 and take away the sum of its digits. What do you get?
  9. 9.?724 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 33 and take away the sum of its digits. What do you get?
  11. 11.Take 59 and take away the sum of its digits. What do you get?
  12. 12.Take 98 and take away the sum of its digits. What do you get?
  13. 13.?871 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?923 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.2?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.25?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?506 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.6?81 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.Take 23 and take away the sum of its digits. What do you get?
  21. 21.6?39 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.21? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.1?79 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 34 and take away the sum of its digits. What do you get?
  25. 25.?669 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?552 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.51?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 47 and take away the sum of its digits. What do you get?
  29. 29.Take 37 and take away the sum of its digits. What do you get?
  30. 30.Take 31 and take away the sum of its digits. What do you get?
  31. 31.?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?770 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 63 and take away the sum of its digits. What do you get?
  34. 34.Take 35 and take away the sum of its digits. What do you get?
  35. 35.?349 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?790 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.6?69 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 13 and take away the sum of its digits. What do you get?
  39. 39.78?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?672 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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