Chapter 4 - Number Representation and Calculation - 4.3 Computation in Positional Systems - Exercise Set 4.3 - Page 234: 13

$13_{four}$

$2$ is less than 3, borrow one four from the next column $(4+2)-3 =3_{ten}=3_{four}$ $\left[\begin{array}{lll} & 3^{(*)} & 2_{four}\\ - & 1 & 3_{four}\\ - & - & -\\ & & 3_{four} \end{array}\right]$ Next column: we borrowed 1 from 3, subtract $2-1=1_{ten}=1_{four}$ record (no borrowing) $\left[\begin{array}{lll} & 3^{(*)} & 2_{four}\\ - & 1 & 3_{four}\\ - & - & -\\ & 1 & 3_{four} \end{array}\right]$ Check in base 10: $14-7=7$