What is 290 in scientific notation?
2.9 x 10², note that the decimal point moved 2 places to the left (from 290 to 2.9) so the exponent is positive 2. If the decimal point moves to the right, then the exponent is negative.
Why do scientist need scientific notation?
To keep the others out, it's more about exclusion than clarity (it makes easy things seem hard). Also the word 'after' is a preposition.
How do you write 4 and 8 thousandths in standard form?
4 and 8 thousandths (4.008) in standard form is 4.008 × 100