Baby anna wants to arrange 12 blocks in a row
12 blocks are arranged in a row having 12 places
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12 blocks can be used in first place. 11 blocks can be used in second place.
10 blocks can be used in third place and so on
12, 11, 10, 9, 8, 7, 6, 5, 4 ,3, 2, 1
12 * 11 * 10 * 9 * 8 * 7 * 6 * 5 * 4 * 3 * 2 * 1 can be written as 12!
12! = 12 * 11 * 10 * 9 * 8 * 7 * 6 * 5 * 4 * 3 * 2 * 1 = 479,001,600
She can make 479,001,600 different arrangements.