Inserting three fraction between 12 and 57
If ab and cd are two fractions, then a+cb+d is a fraction that lies between them.
By using above property, fraction between 12and 57 is,
1+52+7=69 =23
fraction between 12 and 23 is,
1+22+3=35
fraction between 23 and 57 is,
2+53+7=710
Hence, 23,35 and 710 are the three fractions between 12 and 57