## Thinking Mathematically (6th Edition)

$2$; $0 \text{ and } 1$
The numeral $1101_{\text{two}}$ has a base of $2$. The digit symbols are the counting numbers less than the base $2$. Thus, the digit symbols are $0, 1$. Therefore, the missing expressions in the given statement (in order) are: $2$; $0 \text{ and } 1$