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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 7 · 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 99 and take away the sum of its digits. What do you get?
  2. 2.?856 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.16?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.7?66 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. 6.1?93 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.878? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.6?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.6?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 93 and take away the sum of its digits. What do you get?
  11. 11.Take 47 and take away the sum of its digits. What do you get?
  12. 12.150? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 34 and take away the sum of its digits. What do you get?
  14. 14.35? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 11 and take away the sum of its digits. What do you get?
  16. 16.Take 46 and take away the sum of its digits. What do you get?
  17. 17.84?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.?190 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?967 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 54 and take away the sum of its digits. What do you get?
  21. 21.Take 30 and take away the sum of its digits. What do you get?
  22. 22.Take 74 and take away the sum of its digits. What do you get?
  23. 23.Take 62 and take away the sum of its digits. What do you get?
  24. 24.36?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.415? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.61?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.288? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 95 and take away the sum of its digits. What do you get?
  29. 29.54?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?277 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.74?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.2?77 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 77 and take away the sum of its digits. What do you get?
  34. 34.?54 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.17?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.741? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 25 and take away the sum of its digits. What do you get?
  38. 38.Take 33 and take away the sum of its digits. What do you get?
  39. 39.?601 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?85 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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