Evaluate 15*5

Multiply ${\displaystyle 5}$ by ${\displaystyle 5}$. Place the ones digit ${\displaystyle \left(5\right)}$ in the result line and carry the tens digit ${\displaystyle \left(2\right)}$. There is one result line for each digit in ${\displaystyle 5}$.

Multiply ${\displaystyle 5}$ by ${\displaystyle 1}$ and add the carried ${\displaystyle 2}$. Place the result in the next column in the result line. There is one result line for each digit in ${\displaystyle 5}$.

Add the numbers in each column. In this case, add ${\displaystyle 5}$, then place the ${\displaystyle 5}$ in the result line.

Add the numbers in each column. In this case, add ${\displaystyle 7}$, then place the ${\displaystyle 7}$ in the result line.