A wire of $1\Omega$  has length of 1m.  it is stretched till its length increases by 25%.  The percentage change in resistance to the nearest integer is 

Resistance  $\frac{\rho l}{A}=\frac{\rho l}{\left(vol.\right)}$  or $R\propto l^2$

or  $\frac{R_1}{R_2}=\frac{l_1^2}{l_2^2}$

As length increases 25%,if $l_1=l_{ }$ then $l_2=l+l\times \frac{25}{100}=1.25l$

$\therefore \frac{R}{R_2}=\frac{l^2}{{\left(1.25l\right)}^2}or,R_2=1.5625R$

$\therefore \%$ increases in resistance R=56%