Misc: what do most classical guitars have 19 of?

Questions

Most people blink about ______ times a day?

The human body has enough fat to produce ___ bars of soap?

The human head is a quarter of our total length at birth, but only an eighth of our total length by the time we reach?

There is no single word given to describe the back of the?

From fertilisation to birth, a baby's weigh increase ________ times?