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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 219 · 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. 1.157? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.408? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 16 and take away the sum of its digits. What do you get?
  4. 4.?322 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 83 and take away the sum of its digits. What do you get?
  6. 6.Take 74 and take away the sum of its digits. What do you get?
  7. 7.?832 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.517? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?883 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?038 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?59 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.349? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.47?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 43 and take away the sum of its digits. What do you get?
  15. 15.Take 57 and take away the sum of its digits. What do you get?
  16. 16.Take 89 and take away the sum of its digits. What do you get?
  17. 17.Take 40 and take away the sum of its digits. What do you get?
  18. 18.75?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?71 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 23 and take away the sum of its digits. What do you get?
  21. 21.?583 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.5?74 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.Take 28 and take away the sum of its digits. What do you get?
  24. 24.6?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?664 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.Take 98 and take away the sum of its digits. What do you get?
  27. 27.Take 41 and take away the sum of its digits. What do you get?
  28. 28.Take 21 and take away the sum of its digits. What do you get?
  29. 29.Take 86 and take away the sum of its digits. What do you get?
  30. 30.Take 13 and take away the sum of its digits. What do you get?
  31. 31.374? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?731 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?456 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.77? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.8?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.2?19 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?349 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 30 and take away the sum of its digits. What do you get?
  39. 39.?458 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.5?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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