You Do Need power plug adapter while traveling from Bangladesh to Mongolia.

Here is Why You Need An Adapter

The outlet and plug type used in Mongolia are C and E and in Bangladesh are A, C, D, G and K. This is how they look like.

Bangladesh

In Bangladesh, outlets of type A, C, D, G and K are in use.

Type A

Type C

Type D

Type G

Type K

Mongolia

In Mongolia, outlets of type C and E are in use.

Type C

Type E