Assume the bond was originally issued at a premium and there remains
$90 in the umamortized premium account. The bonds are retired for 90 or $900.
Bonds Payable $1,000
Unamortized Bond Premium $90
Gain on Retirement (extraordinary) $190
Cash $900
Assume that the same bond is retired at 110 or $1,100
Bonds Payable $1,000
Unamortized Bond Premium $90
Loss on Retirement (extraordinary) $10
Cash $1,100