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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 302 · 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. 1.46?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.7?86 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.4?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.469? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 25 and take away the sum of its digits. What do you get?
  6. 6.8?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.399? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.507? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.884? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.7?34 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?29 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.?583 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 32 and take away the sum of its digits. What do you get?
  15. 15.Take 67 and take away the sum of its digits. What do you get?
  16. 16.Take 14 and take away the sum of its digits. What do you get?
  17. 17.?908 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.891? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.Take 38 and take away the sum of its digits. What do you get?
  20. 20.54?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 21 and take away the sum of its digits. What do you get?
  22. 22.Take 56 and take away the sum of its digits. What do you get?
  23. 23.481? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.?166 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 44 and take away the sum of its digits. What do you get?
  26. 26.Take 92 and take away the sum of its digits. What do you get?
  27. 27.Take 62 and take away the sum of its digits. What do you get?
  28. 28.150? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.726? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?517 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.8?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.456? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?322 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?425 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 64 and take away the sum of its digits. What do you get?
  36. 36.73?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?856 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.Take 60 and take away the sum of its digits. What do you get?
  39. 39.Take 42 and take away the sum of its digits. What do you get?
  40. 40.Take 99 and take away the sum of its digits. What do you get?

Answer key

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

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