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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 715 · 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 77 and take away the sum of its digits. What do you get?
  2. 2.618? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 98 and take away the sum of its digits. What do you get?
  4. 4.Take 85 and take away the sum of its digits. What do you get?
  5. 5.180? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.7?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.8?84 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 73 and take away the sum of its digits. What do you get?
  9. 9.5?83 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.3?88 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 60 and take away the sum of its digits. What do you get?
  12. 12.748? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 99 and take away the sum of its digits. What do you get?
  14. 14.Take 80 and take away the sum of its digits. What do you get?
  15. 15.Take 37 and take away the sum of its digits. What do you get?
  16. 16.3?13 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 52 and take away the sum of its digits. What do you get?
  19. 19.Take 92 and take away the sum of its digits. What do you get?
  20. 20.Take 44 and take away the sum of its digits. What do you get?
  21. 21.608? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 33 and take away the sum of its digits. What do you get?
  23. 23.?54 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 15 and take away the sum of its digits. What do you get?
  25. 25.Take 29 and take away the sum of its digits. What do you get?
  26. 26.Take 91 and take away the sum of its digits. What do you get?
  27. 27.?523 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 43 and take away the sum of its digits. What do you get?
  29. 29.333? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.34?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.88?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 23 and take away the sum of its digits. What do you get?
  33. 33.446? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 47 and take away the sum of its digits. What do you get?
  35. 35.8?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.81? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.504? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.203? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.3?49 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.894? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

  1. 63
  2. 3
  3. 81
  4. 72
  5. 9
  6. 8
  7. 7
  8. 63
  9. 2
  10. 8
  11. 54
  12. 8
  13. 81
  14. 72
  15. 27
  16. 2
  17. 6
  18. 45
  19. 81
  20. 36
  21. 4
  22. 27
  23. 9
  24. 9
  25. 18
  26. 81
  27. 8
  28. 36
  29. 9
  30. 3
  31. 6
  32. 18
  33. 4
  34. 36
  35. 8
  36. 9
  37. 9
  38. 4
  39. 2
  40. 6

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