Let two decimal numbers are 2.5 and 1.2

Now, 2.5 * 1.2 = 3.00                 {place decimal point after two place from unit place}

Again let two numbers are 25 and 0.5

Now, 25 * 0.5 = 12.5                 {place decimal point after one place from unit place}

In this way, we multiply decimal numbers.

Hope you got the point.