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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 107 · 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 70 and take away the sum of its digits. What do you get?
  2. 2.?217 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.306? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 76 and take away the sum of its digits. What do you get?
  5. 5.?403 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 36 and take away the sum of its digits. What do you get?
  7. 7.?004 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 31 and take away the sum of its digits. What do you get?
  9. 9.7?58 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.8?51 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.5?78 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?205 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.90? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?040 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 73 and take away the sum of its digits. What do you get?
  16. 16.106? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 34 and take away the sum of its digits. What do you get?
  18. 18.Take 46 and take away the sum of its digits. What do you get?
  19. 19.Take 43 and take away the sum of its digits. What do you get?
  20. 20.Take 71 and take away the sum of its digits. What do you get?
  21. 21.7?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.5?08 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?011 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 69 and take away the sum of its digits. What do you get?
  25. 25.Take 47 and take away the sum of its digits. What do you get?
  26. 26.?390 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.8?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?597 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.81? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.86? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.Take 19 and take away the sum of its digits. What do you get?
  32. 32.?273 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?734 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.3?32 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 13 and take away the sum of its digits. What do you get?
  36. 36.47?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.5?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.305? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 88 and take away the sum of its digits. What do you get?
  40. 40.?780 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. 8
  3. 9
  4. 63
  5. 2
  6. 27
  7. 5
  8. 27
  9. 7
  10. 4
  11. 7
  12. 2
  13. 9
  14. 5
  15. 63
  16. 2
  17. 27
  18. 36
  19. 36
  20. 63
  21. 1
  22. 5
  23. 7
  24. 54
  25. 36
  26. 6
  27. 7
  28. 6
  29. 9
  30. 4
  31. 9
  32. 6
  33. 4
  34. 1
  35. 9
  36. 6
  37. 3
  38. 1
  39. 72
  40. 3

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