Your number in decimal form is
3,000,000
.
To get to standard scientific notation, we move the decimal point so there is only one non-zero digit in front of the decimal point.
So,
3,000,000
becomes
3.000,000
.
The trailing zeroes are not significant, so
3.000,000
becomes
3
.
We moved the decimal point six places, so the exponent is
6
.
We moved the decimal point to the left, so the exponent is positive.
The exponential part is therefore
10
6
.
3,000,000=3 X10^6
