Problem 5 with the help of shell expansion

proc 100s {} {
    set N [join {1 2 3 4 5 6 7 8 9} "{+,-,}"]
    set x [exec sh -c [list echo $N]]
    foreach i $x {
	if {[expr $i] == 100} {
	    lappend result $i
	}
    }
    return $result
}