## Thinking Mathematically (6th Edition)

$15760_{nine}$
Rightmost column: $4+5=9=1\times 9+0\times 1=10_{nine}$ record the $0$, carry the 1. $\left[\begin{array}{lllll} & & & 1 & \\ & 6 & 7 & 8 & 4_{nine}\\ + & 7 & 8 & 6 & 5_{nine}\\ & - & - & - & -\\ & & & & 0_{nine} \end{array}\right.$ Next column: $1+8+6=15=1\times 9+6\times 1=16_{nine}$ record the $6$, carry the 1. $\left[\begin{array}{lllll} & & 1 & 1 & \\ & 6 & 7 & 8 & 4_{nine}\\ + & 7 & 8 & 6 & 5_{nine}\\ & - & - & - & -\\ & & & 6 & 0_{nine} \end{array}\right.$ Next column: $1+7+8=16=1\times 9+7\times 1=17_{nine}$ record the $7$, carry the 1. $\left[\begin{array}{lllll} & 1 & 1 & 1 & \\ & 6 & 7 & 8 & 4_{nine}\\ + & 7 & 8 & 6 & 5_{nine}\\ & - & - & - & -\\ & & 7 & 6 & 0_{nine} \end{array}\right.$ Next column: $1+6+7=14=1\times 9+5\times 1=15_{nine}$ record the $15$, Result =$15760_{nine}$