We use a period at the end of an indirect question, which describes a question but does not ask one directly.
Dad asked us why we hadn’t slept last night.
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
The correct answer is
The smallest number is the one that comes first while counting.
To arrange the given numbers in order from smallest to greatest, find the smallest number among all the given numbers.
21,27,23
21 is the smallest number.