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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 170 · 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 83 and take away the sum of its digits. What do you get?
  2. 2.750? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.?708 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.186? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 19 and take away the sum of its digits. What do you get?
  6. 6.Take 39 and take away the sum of its digits. What do you get?
  7. 7.Take 40 and take away the sum of its digits. What do you get?
  8. 8.346? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.6?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 55 and take away the sum of its digits. What do you get?
  11. 11.?444 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.149? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 15 and take away the sum of its digits. What do you get?
  14. 14.Take 54 and take away the sum of its digits. What do you get?
  15. 15.831? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.440? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.5?95 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?884 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 36 and take away the sum of its digits. What do you get?
  21. 21.Take 88 and take away the sum of its digits. What do you get?
  22. 22.?986 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 77 and take away the sum of its digits. What do you get?
  24. 24.?412 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 50 and take away the sum of its digits. What do you get?
  26. 26.Take 81 and take away the sum of its digits. What do you get?
  27. 27.25?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.148? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 58 and take away the sum of its digits. What do you get?
  30. 30.?497 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.26?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 24 and take away the sum of its digits. What do you get?
  33. 33.Take 22 and take away the sum of its digits. What do you get?
  34. 34.Take 20 and take away the sum of its digits. What do you get?
  35. 35.4?58 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.?485 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 28 and take away the sum of its digits. What do you get?
  38. 38.24?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.22?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?835 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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