13. Invert the 10-Coin Triangle Ten identical coins are arranged on the table in the shape of a triangle that points downward, as shown below:* * * * * * * * * *By moving exactly three coins to new positions, turn the triangle so that it points upward (its apex at the top and a base of four coins at the bottom).All other coins must stay where they are, and no extra coins may be added or removed.How can you do it? Added 23 September 2009 Show Hint Show Solution Hint: Focus on the three coins that are closest to the centre of the figure; they will all need to move. Solution: Number the starting positions from left to right, top to bottom:1 2 3 4 5 6 7 8 9 10Move the following three coins:Coin 2 → position of 10 (the current apex).Coin 3 → position of 8 (left coin in the third row).Coin 6 → position of 9 (right coin in the third row).The new layout is: * (coin 2) * * (coins 3 and 6) * * * (coins 1,5,4) * * * * (coins 7,8,9,10)This forms a triangle with its point at the top and a base of four coins at the bottom, satisfying the conditions with only three moves.
Comments (2)
original
1 2 3 4
5 6 7
8 9
0
new
0
1 2
5 6 7
8 9 3 4
changed pennies number are 0,3,4
: good job nitin267 :D
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