Base Conversions

#!/bin/bash
echo -n "Enter a numnber: "
read n
echo -n "$n's base is: B->Bin O->Oct D->Dec H->Hex: "
read choice
case $choice in
    B):
        echo 'obase=10; ibase=2; '$n'' | bc
        echo 'obase=16; ibase=2; '$n'' | bc
        echo 'obase=8; ibase=2; '$n'' | bc;;
    D):
        echo 'obase=2; ibase=10; '$n'' | bc
        echo 'obase=16; ibase=10; '$n'' | bc
        echo 'obase=8; ibase=10; '$n'' | bc;;
    O):
        echo 'obase=10; ibase=8; '$n'' | bc
        echo 'obase=2; ibase=8; '$n'' | bc
        echo 'obase=16; ibase=8; '$n'' | bc;;
    H):
        echo 'obase=10; ibase=16; '$n'' | bc
        echo 'obase=2; ibase=16; '$n'' | bc
        echo 'obase=8; ibase=16; '$n'' | bc;;
esac