Let side of S1 = a ... area of S1 = a2
diag of S2 = a ==> side of S2 = a/√2 ... area of S2 = a2/2
diag of S3 = a/√2 ==> side of S3 = a/2 ... area of S3 = a2/4
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Area of Sn = a2/2n-1
now a = 10cm
So, 100/2n-1 < 1
==> 2n-1 > 100
==> n-1 > 7
==> n>8