Video Transcript
Work out the value of five times 10 to
the 5 times 8.2 times 10 to the power of 11, giving your answer in scientific notation.
Well, again, multiplication is
commutative, so it doesn’t matter whether we’ve got the parentheses and what order we write
those in. So, I’m going to do five times 8.2 times
10 to the power of five times 10 to the power of 11, in that order. Now, five times 8.2 is 41. And if I multiplied by 10 to the power of
five, that’s multiplying by 10 five times, and then by 10 to the power of 11, that’s
multiplying by 10 another 11 times, that’s a total of 16 times. So, it’s times 10 to the power of 16. So, that’s equal to 41 times 10 to the
power of 16.
But wait a minute! That’s not our answer! This number here has to be between one
and 10. 41 isn’t between one and 10. But look, I could write it as 4.1 times
10 to the power of something. Well, in fact, in this case it would be
times 10 to the power of one because I need to multiply 4.1 by 10 once to turn it into
41. So, 41 is equal to 4.1 times 10 to the
power of one.
And that’s the number that has to be
multiplied by 10 to the power of 16. Well, we can see that we’ve got 4.1 times
10 once times 10 another 16 times, which means that’s times 10 17 times in total. And there we have it. We’ve now got our number in proper
scientific notation. That first term is 4.1. That is between one and 10. And we’ve got times 10 to the power of
17.
