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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 544 · 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. 1.886? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.67?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.90? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.70?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.78? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?119 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.279? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.Take 52 and take away the sum of its digits. What do you get?
  9. 9.1?74 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.646? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.25?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 98 and take away the sum of its digits. What do you get?
  13. 13.420? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.8?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 25 and take away the sum of its digits. What do you get?
  16. 16.Take 60 and take away the sum of its digits. What do you get?
  17. 17.Take 21 and take away the sum of its digits. What do you get?
  18. 18.52?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?890 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.514? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.3?89 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 40 and take away the sum of its digits. What do you get?
  23. 23.18?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.703? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 78 and take away the sum of its digits. What do you get?
  26. 26.22?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.70?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.Take 49 and take away the sum of its digits. What do you get?
  29. 29.Take 86 and take away the sum of its digits. What do you get?
  30. 30.60?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?611 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 95 and take away the sum of its digits. What do you get?
  33. 33.?303 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 75 and take away the sum of its digits. What do you get?
  35. 35.6?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.3?80 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.790? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?521 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.288? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 27 and take away the sum of its digits. What do you get?

Answer key

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

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