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Digit Sum Magic Worksheet

Maths tricks trick 10: Digit-sum magic · Set 573 · 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. 1.6?55 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  2. 2.6?66 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  3. 3.207? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  4. 4.Take 98 and take away the sum of its digits. What do you get?
  5. 5.622? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  6. 6.26?2 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  7. 7.Take 44 and take away the sum of its digits. What do you get?
  8. 8.?628 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  9. 9.Take 88 and take away the sum of its digits. What do you get?
  10. 10.45?9 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  11. 11.Take 92 and take away the sum of its digits. What do you get?
  12. 12.16?7 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  13. 13.42?1 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  14. 14.?517 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  15. 15.Take 87 and take away the sum of its digits. What do you get?
  16. 16.?893 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  17. 17.Take 71 and take away the sum of its digits. What do you get?
  18. 18.Take 51 and take away the sum of its digits. What do you get?
  19. 19.50?6 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  20. 20.?395 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  21. 21.Take 49 and take away the sum of its digits. What do you get?
  22. 22.7?5 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  23. 23.8?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  24. 24.Take 94 and take away the sum of its digits. What do you get?
  25. 25.?074 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  26. 26.1?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  27. 27.43?3 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  28. 28.423? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  29. 29.52?0 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  30. 30.?970 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  31. 31.200? is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  32. 32.Take 74 and take away the sum of its digits. What do you get?
  33. 33.Take 66 and take away the sum of its digits. What do you get?
  34. 34.Take 95 and take away the sum of its digits. What do you get?
  35. 35.?313 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  36. 36.2?50 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  37. 37.51?4 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  38. 38.?920 is in the 9 times table. One digit is hidden, and it is not 0. What is the hidden digit?
  39. 39.Take 45 and take away the sum of its digits. What do you get?
  40. 40.640? 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. 9
  3. 9
  4. 81
  5. 8
  6. 8
  7. 36
  8. 2
  9. 72
  10. 9
  11. 81
  12. 4
  13. 2
  14. 5
  15. 72
  16. 7
  17. 63
  18. 45
  19. 7
  20. 1
  21. 36
  22. 6
  23. 1
  24. 81
  25. 7
  26. 3
  27. 8
  28. 9
  29. 2
  30. 2
  31. 7
  32. 63
  33. 54
  34. 81
  35. 2
  36. 2
  37. 8
  38. 7
  39. 36
  40. 8

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