MATL, 12 bytes (cracked by @tehtmi)

'Un&0P'/^:+1

No rounding; uses floating point.

Intended solution (different from that found by @tehtmi):

:&+n10U'P'/^

###Explanation

:&+ % Create a matrix of size n ×ばつ n, where n is implicit input
n % Number of elements. Gives n^2
10U % 10 squared. Gives 100
'P' % 'P' (ASCII code 80)
/ % Divide. Gives 1.25
^ % Power. Implicit display

MATL, 12 bytes (cracked by @tehtmi)

'Un&0P'/^:+1

No rounding; uses floating point.

Intended solution (different from that found by @tehtmi):

:&+n10U'P'/^

Explanation

:&+ % Create a matrix of size n ×ばつ n, where n is implicit input
n % Number of elements. Gives n^2
10U % 10 squared. Gives 100
'P' % 'P' (ASCII code 80)
/ % Divide. Gives 1.25
^ % Power. Implicit display

MATL, 12 bytes (cracked by @tehtmi)

'Un&0P'/^:+1

No rounding; uses floating point.

Intended solution (different from that found by @tehtmi):

:&+n10U'P'/^

###Explanation

:&+ % Create a matrix of size n ×ばつ n, where n is implicit input
n % Number of elements. Gives n^2
10U % 10 squared. Gives 100
'P' % 'P' (ASCII code 80)
/ % Divide. Gives 1.25
^ % Power. Implicit display

MATL, 12 bytes (cracked by @tehtmi)

'Un&0P'/^:+1

No rounding; uses floating point.

Intended solution (different from that found by @tehtmi):

:&+n10U'P'/^

###Explanation

:&+ % Create a matrix of size n ×ばつ n, where n is implicit input
n % Number of elements. Gives n^2
10U % 10 squared. Gives 100
'P' % 'P' (ASCII code 80)
/ % Divide. Gives 1.25
^ % Power. Implicit display

MATL, 12 bytes

'Un&0P'/^:+1

No rounding; uses floating point.

EDIT Sorry everyone, there was a mistake. Former O should be 0. Corrected now. (I would downvote myself for this if I could).

MATL, 12 bytes (cracked by @tehtmi )

'Un&0P'/^:+1

No rounding; uses floating point.

Intended solution (different from that found by @tehtmi):

:&+n10U'P'/^

###Explanation

:&+ % Create a matrix of size n ×ばつ n, where n is implicit input
n % Number of elements. Gives n^2
10U % 10 squared. Gives 100
'P' % 'P' (ASCII code 80)
/ % Divide. Gives 1.25
^ % Power. Implicit display