Do you annex a zero when multiplying decimals?

Answer 1

Multiply decimals exactly as though there are no decimals either number.

If you end up with zeros on the right in your product, keep them throughout the problem.

Count how many digits are to the right of the decimal place on both multipliers, add those numbers, and make sure that is how many digits you have to the right of the decimal in your product.

Example: multiply 0.5 x 1.6~multiply 5 x 16 = 80. ~count the decimal places in the products together - 1 place in 0.5, and 1 place in 1.6 - so 2 places.~move the decimal left two places in the product - 80 becomes 0.80. Now you can drop the useless zero on the end to get 0.8.~check with estimates if you are unsure - half of 1 is 0.5, and half of 2 is 1, and my answer is between those, so I'm good. If I messed up and got 8 or 80 or 800, they are definitely not reasonable, and you should try again.