How to Multiply 3-digit Numbers Having a Zero in the Tens Place

Use this trick to multiply 3-digit numbers having a zero in the tens place in 5 seconds or less.

A 3-digit number is any number that has digits in the ones, tens, and hundreds places. All digits from 100 to 999 are 3-digit numbers.

When the number in the tens place is zero, there is a trick that you can use to perform the multiplication in 5 seconds or less. The very first thing to do is to set up the multiplication vertically. Then, follow the three steps below. 
What is 304 times 205? 
   304 × 205Step 1Multiply the numbers in the hundreds place and write the answer on the left.6Multiply the numbers in the ones place and write the answer on the right.6 20Leave a space between 6 and 20.6      20Step 2Cross multiply as shown in the figure above and add the products.3 × 5 + 4 × 2 = 23Step 3Put 23 between 6 and 20.  304 times 205 = 62320
What is 508 times 406? 
   508 × 406Step 1Multiply the numbers in the hundreds place and write the answer on the left.20Multiply the numbers in the ones place and write the answer on the right.20 48Leave a space between 20 and 48 numbers.20      48Step 2Cross multiply and add the products.5 × 6 + 4 × 8 = 30 + 32 = 62Step 3Put 62 between 20 and 48.  508 times 406 = 206248