Answer:
2.51 x 10^5
Explanation:
Scientific notation gives you a number between 1 and 10 multiplied by a power of ten. In this case, you'll want to use the significant digits, 251, and divide or multiply by a power of ten to get a number between 1 and 10.
251,000 can become 2.51 (which is between 1 and 10) multiplied by 10 to a certain exponent. All you need to do is calculate the exponent.
2.51 x 10^(?) = 251,000
For each power of 10, the decimal moves a space. Since you want the decimal to move 5 spaces, you'll want to multiply 2.51 by 10^5.
2.51 x 10 = 25.1
2.51 x 10^2 = 251
2.51 x 10^3 = 2510
2.51 x 10^4 = 25,100
2.51 x 10^5 = 251,000