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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 400 · 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.?701 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.Take 79 and take away the sum of its digits. What do you get?
  4. 4.70?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.151? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.Take 95 and take away the sum of its digits. What do you get?
  7. 7.Take 47 and take away the sum of its digits. What do you get?
  8. 8.Take 77 and take away the sum of its digits. What do you get?
  9. 9.725? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.Take 29 and take away the sum of its digits. What do you get?
  11. 11.?861 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 19 and take away the sum of its digits. What do you get?
  13. 13.4?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 55 and take away the sum of its digits. What do you get?
  15. 15.?422 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.Take 73 and take away the sum of its digits. What do you get?
  17. 17.749? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.390? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.?210 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.391? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?932 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.Take 66 and take away the sum of its digits. What do you get?
  23. 23.?169 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.55?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.622? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.?003 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.8?95 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.3?30 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.4?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 86 and take away the sum of its digits. What do you get?
  31. 31.?022 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?466 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.5?00 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 49 and take away the sum of its digits. What do you get?
  35. 35.8?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.556? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.278? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.34? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.1?96 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.781? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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