For the first place, Rachel can put any of the 9 blocks, so we have 9 options. For the second place, there will be 8 blocks left, so 8 options in this case. For the third place there will be 7 options and so on. The number of different arrangements is
"N = 9 \\times 8 \\times 7 \\times 6 \\times5 \\times4 \\times 3 \\times 2 \\times 1 = 362\\,880"
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