Well, when multiplying decimals, you would just multiply the numbers regularly, and then we'll add the decimals in the end.
SO,
Multiply 2.36 times 5.4 as if it was 236 times 54, which is 12744. So, since 2.36's decimal is two places to the left from the end of the number, (shown in the attached image), and 5.4's decimal is one place to the left from the end of the number, we can add both places so that it's 2 + 1, which is 3, so from the end of the answer of 12744, we'll move the decimal three places to the left, which gives the final answer to be 12.744. I hope I helped! ^-^