Number Girl

is a Japanese manga series written and illustrated by Tanigawa Nico. The manga was serialized in the Dengeki Daioh magazine and later Dengeki Daiouji. It was published in Japan by ASCII Media Works under the Dengeki Comics NEXT imprint from June 2013.

Synopsis
A 4-koma following a group of sixteen identically cloned middle-school girls attending school in Japan. Each girl is known only by the number imprinted on their right eye, 1 through 16 respectively. Under the instruction of a quick-to-anger Teacher and her fellow "common sense instructor" named Azuma (whose teachings the girls completely disregard), each of the girls develops her own distinct personality. As clones with no prior life experience and lacking common sense, they are not hesitant to speak their minds freely, which frequently brings the wrath of their instructor upon them.

As time passes and they grow, the clone girls start having distinct personalities... but an equal lack of common sense! Watch them not get any better!

(Source: Manga Updates)