scientific notation help?

Question

45, 000, 000 x 220, 000, 000,000.

I got 9.9 x 10 ^18.

However the products is where I differ from the answer.
4.5 x 10 ^7 x 2.2 x 10^11.

How were 7 and 11 arrived at? 7 + 11 = 18. And there are only 16 zero's so can someone please explain why it wouldn't be to the power of 6 and 10?

I have just finished going over the maths book various times, before I asked the question.

Answer 1

though there is only 16 0's, you have to count the place where the decimal is at also. for example:
45,000,000=4.5x10^7 becasue you move the decimal over 7 places to get 45,000,000.

220,000,000,000=2.2x10^11 because of the decimal placement also

Answer 2

In scientific notation, each number is expressed by a decimal with one digit before the decimal place, multiplied by a power of ten. Granted, you could write 45,000,000 as 45 * 10^6, but tha wouldn't be proper scientific notation. For that you would have to write 4.5 * 10^7. It doesn't matter how many zeros there are. 44,444,444 would still be 4.4444444 * 10^7.

Answer 3

16 zeros plus 1 zeros from 2.2 * 10^1 plus 1 zero from 4.5*10^1
So the total is 16+1+1= 18 zeros

2.2 * 4.5 = 9.9
10^11 * 10^7 = 10^18

Final answer is 9.9* 10^18

Answer 4

7 and 11 represent how many places the decimal place was moved. The decimal is not present in 45 000 000, but it should be after the last 0 (ie. 45 000 000. )

Answer 5

45,000,000 has 6 zeros but
45 = 4.5 x 10
therefore 45,000,000 = 4.5x10^7

similarly 220,000,000,000 has 10 zeros and 22=2.2x10

therefore 220,000,000,000 = 2.2x10^11

hence the ans is 9.9x10^18

Answer 6

45,000,000 = 4.5 * 10,000,000 = 4.5 *10^7
220,000,000,000 = 2.2 * 100,000,000 = 2.2*10^11

4.5*10^7 * 2.2*10^11 = (4.5*2.2)*(10^7*10^11) = 9.9*10^18

You really need to review your math book.