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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 675 · 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 98 and take away the sum of its digits. What do you get?
  2. 2.77?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 47 and take away the sum of its digits. What do you get?
  4. 4.5?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.?597 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.1?47 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?511 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 43 and take away the sum of its digits. What do you get?
  9. 9.1?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.42?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.34?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.20?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.7?95 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.448? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 69 and take away the sum of its digits. What do you get?
  16. 16.?019 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 84 and take away the sum of its digits. What do you get?
  18. 18.1?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 56 and take away the sum of its digits. What do you get?
  20. 20.74?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?989 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.80?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.6?16 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?773 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.71?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.4?35 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.6?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?35 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.18?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?103 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 23 and take away the sum of its digits. What do you get?
  32. 32.11? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.31?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.36?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?973 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 88 and take away the sum of its digits. What do you get?
  37. 37.Take 54 and take away the sum of its digits. What do you get?
  38. 38.?794 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.277? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 21 and take away the sum of its digits. What do you get?

Answer key

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

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