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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 569 · 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.?046 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.44?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.79?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.35?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  5. 5.59?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.?082 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.8?52 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  8. 8.5?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.22?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  10. 10.22?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.31?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.718? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.?10 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.4?8 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 57 and take away the sum of its digits. What do you get?
  16. 16.Take 30 and take away the sum of its digits. What do you get?
  17. 17.32? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.406? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  19. 19.75?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.229? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 18 and take away the sum of its digits. What do you get?
  22. 22.76?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.?701 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.2?47 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.?820 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.96? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.Take 78 and take away the sum of its digits. What do you get?
  28. 28.839? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.Take 40 and take away the sum of its digits. What do you get?
  30. 30.47?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.?749 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.669? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.1?87 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  34. 34.?120 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.?404 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.Take 80 and take away the sum of its digits. What do you get?
  37. 37.?030 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.826? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.452? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.64?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?

Answer key

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

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