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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 670 · 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.?986 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 73 and take away the sum of its digits. What do you get?
  3. 3.177? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 52 and take away the sum of its digits. What do you get?
  5. 5.Take 79 and take away the sum of its digits. What do you get?
  6. 6.Take 17 and take away the sum of its digits. What do you get?
  7. 7.4?44 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?88 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.?354 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.?640 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.52?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.40?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.Take 65 and take away the sum of its digits. What do you get?
  14. 14.8?72 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?070 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.5?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?298 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 60 and take away the sum of its digits. What do you get?
  19. 19.?37 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.707? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.838? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.4?61 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.1?62 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 24 and take away the sum of its digits. What do you get?
  25. 25.Take 35 and take away the sum of its digits. What do you get?
  26. 26.Take 66 and take away the sum of its digits. What do you get?
  27. 27.7?49 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. 29.30? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.39? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 54 and take away the sum of its digits. What do you get?
  32. 32.Take 13 and take away the sum of its digits. What do you get?
  33. 33.?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?69 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.31?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.8?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.703? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.749? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.?169 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 62 and take away the sum of its digits. What do you get?

Answer key

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

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