Question

Replace $*$ by a digit to make the number exactly divisible by $9$

$91*67$

Answer 1

A number is divisible by $9$ if the sum of its digits is divisible by $9$.

$91*67$$=$$9+1+*+6+7=23+*$

Observe that when $*$$=$$4$, then the sum of its digits is divisible by $9$

Hence, the $*$ will replace by $4$.