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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 441 · 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.?970 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.31?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.5?02 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 26 and take away the sum of its digits. What do you get?
  5. 5.8?42 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.2?25 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 79 and take away the sum of its digits. What do you get?
  8. 8.Take 38 and take away the sum of its digits. What do you get?
  9. 9.Take 74 and take away the sum of its digits. What do you get?
  10. 10.Take 30 and take away the sum of its digits. What do you get?
  11. 11.7?12 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  12. 12.549? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.437? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.Take 18 and take away the sum of its digits. What do you get?
  15. 15.Take 33 and take away the sum of its digits. What do you get?
  16. 16.160? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.?346 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  18. 18.Take 55 and take away the sum of its digits. What do you get?
  19. 19.Take 80 and take away the sum of its digits. What do you get?
  20. 20.?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.?647 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  22. 22.605? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.39?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.1?05 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  25. 25.79?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.6?15 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.74?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.?080 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.?295 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.6?84 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.897? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.?60 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  33. 33.Take 48 and take away the sum of its digits. What do you get?
  34. 34.108? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  35. 35.Take 52 and take away the sum of its digits. What do you get?
  36. 36.Take 53 and take away the sum of its digits. What do you get?
  37. 37.Take 72 and take away the sum of its digits. What do you get?
  38. 38.?490 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.319? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  40. 40.26?6 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. 4
  3. 2
  4. 18
  5. 4
  6. 9
  7. 63
  8. 27
  9. 63
  10. 27
  11. 8
  12. 9
  13. 4
  14. 9
  15. 27
  16. 2
  17. 5
  18. 45
  19. 72
  20. 6
  21. 1
  22. 7
  23. 6
  24. 3
  25. 8
  26. 6
  27. 6
  28. 1
  29. 2
  30. 9
  31. 3
  32. 3
  33. 36
  34. 9
  35. 45
  36. 45
  37. 63
  38. 5
  39. 5
  40. 4

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