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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 413 · 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. 1.47? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 43 and take away the sum of its digits. What do you get?
  3. 3.Take 30 and take away the sum of its digits. What do you get?
  4. 4.40?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.670? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 12 and take away the sum of its digits. What do you get?
  7. 7.24?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 53 and take away the sum of its digits. What do you get?
  9. 9.7?17 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 58 and take away the sum of its digits. What do you get?
  11. 11.Take 44 and take away the sum of its digits. What do you get?
  12. 12.?299 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.1?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 77 and take away the sum of its digits. What do you get?
  15. 15.47?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?829 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 11 and take away the sum of its digits. What do you get?
  18. 18.85?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.748? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 98 and take away the sum of its digits. What do you get?
  21. 21.Take 45 and take away the sum of its digits. What do you get?
  22. 22.?173 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?894 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 89 and take away the sum of its digits. What do you get?
  25. 25.30?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.5?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.3?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.7?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?233 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 13 and take away the sum of its digits. What do you get?
  31. 31.318? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?043 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.65?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.21? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.399? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 47 and take away the sum of its digits. What do you get?
  37. 37.55?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.5?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?304 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 97 and take away the sum of its digits. What do you get?

Answer key

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

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