1,111,111,111,111,111,111/Historical Note

Historical Note on $1 \, 111 \, 111 \, 111 \, 111 \, 111 \, 111$
The prime nature of $1 \, 111 \, 111 \, 111 \, 111 \, 111 \, 111$ was discovered by a reader of one of 's newspaper puzzle columns in $1918$.