Question

What is the first step when adding 1.45 x 108 and 3.9 x 107?

1. Convert both numbers back to standard notation.
2. Convert 1.45 x 108 to 14.5 x 107.
3. Add the numbers in front and multiply the exponents.
4. These problems cannot be added since the exponents do not match.

Answer 1

We need to add 1.45 x 10^8 and 3.9 x 10^7.

Please see..

We have given numbers in scientific form.

We can't add the decimal numbers in front, because those numbers are being multiplied with 10 exponents and the exponents of 10's are not same.

So, we always convert the exponents of 10 as same.

1.45 x 10^8 could be converted to 14.5 x 10^7 to get exponent of 10 as 7 as other number 3.9 x 10^7 also has exponent of 10 as 7.

After this step we can just add the 14.5 and 3.9 and put × 10^7 with it.

So, first correct step is:

2. Convert 1.45 x 108 to 14.5 x 107.