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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 610 · 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. 1.50? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.7?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.Take 71 and take away the sum of its digits. What do you get?
  4. 4.4?46 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.390? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.77?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 58 and take away the sum of its digits. What do you get?
  8. 8.54?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 81 and take away the sum of its digits. What do you get?
  10. 10.?704 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.?031 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.Take 27 and take away the sum of its digits. What do you get?
  13. 13.475? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 88 and take away the sum of its digits. What do you get?
  15. 15.Take 75 and take away the sum of its digits. What do you get?
  16. 16.Take 99 and take away the sum of its digits. What do you get?
  17. 17.?696 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 47 and take away the sum of its digits. What do you get?
  19. 19.Take 38 and take away the sum of its digits. What do you get?
  20. 20.?35 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.4?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.?548 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.7?03 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 22 and take away the sum of its digits. What do you get?
  25. 25.?948 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.5?45 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 20 and take away the sum of its digits. What do you get?
  28. 28.27?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.54?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 46 and take away the sum of its digits. What do you get?
  31. 31.?65 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?40 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.?502 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.Take 56 and take away the sum of its digits. What do you get?
  35. 35.?024 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.280? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.378? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.7?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 82 and take away the sum of its digits. What do you get?
  40. 40.Take 63 and take away the sum of its digits. What do you get?

Answer key

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

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