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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 738 · 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. 1.21? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.62?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.27?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.?296 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.705? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?668 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.?173 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.?465 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 31 and take away the sum of its digits. What do you get?
  10. 10.Take 23 and take away the sum of its digits. What do you get?
  11. 11.84?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.6?11 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.30?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?322 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.?17 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  16. 16.145? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 73 and take away the sum of its digits. What do you get?
  18. 18.Take 16 and take away the sum of its digits. What do you get?
  19. 19.?63 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.53?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.7?75 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.90? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?90 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 11 and take away the sum of its digits. What do you get?
  25. 25.?151 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.50?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 47 and take away the sum of its digits. What do you get?
  28. 28.?583 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?340 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.Take 12 and take away the sum of its digits. What do you get?
  31. 31.1?62 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.2?86 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 62 and take away the sum of its digits. What do you get?
  34. 34.Take 59 and take away the sum of its digits. What do you get?
  35. 35.35?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.568? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.Take 17 and take away the sum of its digits. What do you get?
  38. 38.5?38 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.82? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.Take 22 and take away the sum of its digits. What do you get?

Answer key

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

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