Answer:
Subscript
Step-by-step explanation:
For example
shows 1 atom of Ca and 2 atoms of Cl
Another example

we multiply
Coefficient × subscript × number outside the bracket.......... to find the number of atoms
(Please note: 3 is the coefficient, and if there is no number given then 1 will be the coefficient )
So,
, Ca atoms
, P atoms
, O atoms are present.