What is sex ratio? How is it calculated?

Sex ratio is defined as the number of females per 1,000 males in the population. This information is an important social indicator, to measure the extent of equality between males and females in a society, at a given time. The sex ratio in India has always remained unfavourable for females. The sex ratio of India in 1951 was 946 females per 1,000 males and in 2001, it
declined to 933 females per 1,000 males.