At these times i was 16 years and i was in grade 10. I was having sent-up examination. Mathematics is my little bit top subject and i had pratice number 14 from page no 344 it was theorem. And when i went to write exam i find there came theorem no 12, at tha time i was like really nurvous because there is unfamilar theorem i had pratice number 14 but at that time there i find number 12.