I know the answer is .78, but don’t understand why? .9-.6X.2

Question

asked Feb 16, 2021 126k views

2 Answers

Tang Ke · Answer 1 · 2021-02-18T00:54:35+0000

Explanation:

When you multiply 0.6 and 0.2, you do not get 1.2. Rather, the product would be 0.12.

We have the equation
0.9-(0.6)(0.2)

To show you what is happening, lets convert these numbers into fractions

This would give us
(9)/(10) -((6)/(10))((2)/(10))

Recall that when you multiply two fractions, you multiply the numerators and denominators separately. Doing so gives us

(9)/(10) -(6*2)/(10*10)

Which then becomes

(9)/(10) -(12)/(100)

The last thing we need to do is to create a common denominator

(90)/(100)-(12)/(100)=(78)/(100) =0.78

Another way to see what is happening is by thinking about the numbers in scientific notation. Doing so would give us

9*10^(-1)-(6*10^(-1))(2*10^(-1))

Once we multiply these terms, we get

$9*10^(-1)-6*10^(-1)*2*10^(-1)\\\\9*10^(-1)-12*10^(-2)$

Now we can convert these numbers into decimals to get

0.9-0.12=0.78