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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 828 · 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. 1.71?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.Take 97 and take away the sum of its digits. What do you get?
  3. 3.13?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.725? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.Take 24 and take away the sum of its digits. What do you get?
  6. 6.3?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 49 and take away the sum of its digits. What do you get?
  8. 8.?294 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.36?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 25 and take away the sum of its digits. What do you get?
  11. 11.5?27 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 43 and take away the sum of its digits. What do you get?
  13. 13.12?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 17 and take away the sum of its digits. What do you get?
  15. 15.3?11 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.?510 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.3?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.408? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.3?04 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.Take 61 and take away the sum of its digits. What do you get?
  21. 21.Take 47 and take away the sum of its digits. What do you get?
  22. 22.418? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.2?73 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.6?57 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.Take 91 and take away the sum of its digits. What do you get?
  26. 26.308? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.88?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?998 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?070 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.4?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.198? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 42 and take away the sum of its digits. What do you get?
  33. 33.Take 23 and take away the sum of its digits. What do you get?
  34. 34.7?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?371 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.7?83 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.?680 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?863 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.47?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.?431 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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