Question

Mary simplified an expression and got 12.9x10^4 for her answer in scientific notation. Her friend, Angela, is telling her that her answer is incorrect. Why is Angela telling her she is incorrect? What is the correct way to write that number in scientific notation?

Answer 1

Mary simplified an expression.
`1.29 * 10^(5)` is correct representation in scientific notation.

Solution:

Given that Mary simplified an expression and got
`12.9 * 10^(4)` for answer in scientific notation.

According to Angela, answer is incorrect. Need to find reason why Angela consider
`12.9 * 10^(4)` as incorrect scientific notation and find the correct answer.

Let’s understand what is scientific notation of any number.

Scientific notation is a way of representing number between 1 and 10 including 1 and excluding 10 multiplied by appropriate power of 10.

According to Mary’s simplification the number she is getting is 12.9 but in scientific notation, number must be in between 1 to 10

So
`12.9 * 10^(4)` is not correct scientific notation.

`\text { Let's rewrite } 12.9 * 10^(4) \text { as } 1.29 * 10^(1) * 10^(4)=1.29 * 10^(5)`

Now we got 1.29 which is in between 1 and 10 multiplied by
`10^5`

Hence
`1.29 * 10^(5)` is correct representation in scientific notation.