How did the answer become 0.1

Dear student,
0.0506 = 0.051 up to 3 significant digit as 0.06 is always equal to 0.1 while converting it to 1 significant digit
then ,
0.051 = 0.05 up to 2 significant digit 
then,
0.05 = 0.1 up to 1 significant digit

regards,
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