Formula of even number

Answer 1

if its algebra,

x+x ( if you ad two of the same numbers, the answer is always even 1+1 =2 2+2=4 ...etc)

Y x2 (multiplying a number by 2 is exactally the same as the previous x+x )

Z x10 (any whole number (not decimal) timed by 10 is always even....)