XXX x XXX (any 2 numbers)

Formulas :

( __ x __ )[( __ x __ ) + ( __ x __ )][( __ x __ ) + ( __ x __ ) + ( __ x __ )][( __ x __ ) + ( __ x __ )]( __ x __ )

Example :

121 x 310

( 1 x 3 )[( 1 x 1 ) + ( 2 x 3 )][( 1 x 0 ) + ( 2 x 1 ) + ( 1 x 3 )][( 2 x 0 ) + ( 1 x 1 )]( 1 x 0 )

(3)(1 + 6)(0 + 2 + 3)(0 + 1)(0)

(3)(7)(5)(1)(0)

So, 121 × 310 = 37510