HTML <sub> element


<sub> tag defines the content as subscripted text.

X<sub>1</sub> + Y<sub>1</sub> = 5 

X1 + Y1 = 5

MgCl<sub>2</sub> + 2AgNO<sub>3</sub> = 2AgCl + Mg(NO<sub>3</sub>)2

MgCl2 + 2AgNO3 = 2AgCl + Mg(NO3)2