Now multiply the first number with the $1^{st}$ digit in $2^{nd}$ number to get intermediate results. That is Multiply 86400 with 5. Write the result 432000 at the end leaving 0 spaces to the right like this.
Now multiply the first number with the $2^{nd}$ digit in $2^{nd}$ number to get intermediate results. That is Multiply 86400 with 6. Write the result 518400 at the end leaving 1 spaces to the right like this.
Now multiply the first number with the $3^{rd}$ digit in $2^{nd}$ number to get intermediate results. That is Multiply 86400 with 3. Write the result 259200 at the end leaving 2 spaces to the right like this.