Question

Which of the following is the correct flow for solving $521\times 72$ using lattice method?

• A.
• B.

Answer 1

The correct option is B

$\bullet$ To calculate $521\times 72$ using lattice method, we first separate $521$ as per its face values $5$, $2$ and $1$, and arrange along the table from left to right. And, we write $72$ as per its face values $7$ and $2$ at the farthest right from top to down.


$\bullet$ As the name suggests, in the lattice method, we draw separators which resemble the cone in diamond lattice as shown below.


$\bullet$ Now, we know $1\times 7=7$, $2\times 7=14$, $5\times 7=35$, $1\times 2=2$, $2\times 2=4$ and $5\times 2=10$, which are separated as per their face values by the arrows.


$\bullet$ Next, we write down the numbers just below the cell's position, and do the arrangement from left to right to get the final result of the multiplication.


In the above figure, we can see that if the result after addition is a 2-digits number, the carry will be added to the next section.

$\bullet$ Finally, $521\times 72=37,512$.

Hence, option (b.) is the correct one.