Edmund's Brainteasers
Problem 9
Problem 9: The Hymn Boards
All the problems up till now have been fictitious. This problem, however, is non-fiction!
All Saints Church has two hymn boards where the 5 hymn numbers are displayed. There are 'digit cards' each containing one of the numbers 0, 1, 2, 3, 4, 5, 6, 7, 8 and these are slid into the appropriate slot to make up the hymn numbers. No digit card is necessary for the digit 9 since 6 is inserted up-side-down. Our hymnbook contains 542 hymns. What is the least number of 'digit cards' needed to display any choice of hymns on the two hymn boards?