Why matlab not simplify my answer?

Hello can you hel me please

Here is my script:

u=symunit;

L= input('Lenght of where you would like to measure the deflection in meter: ')*u.m
L=unitConvert(L,u.mm);
W=8500*u.N; 
E=42000 *u.N/u.mm^2;
I=10*(10^6)*u.mm^4;

D=(W*L^3)/(8*E*I)

and the answer is :

D =
(53125/21)*[mm]

How can I get matlab to simplify this for me? Thanks

Answer 1

[madhan ravi]

D=vpa((W*L^3)/(8*E*I))

[Milan Sumegi]

Thank you very much ;)

[madhan ravi]

Anytime :)