Answer: 3*10^2
====================================
Work Shown:
7321 = 7000 + 300 + 20 + 1
7321 = 7*1000 + 3*100 + 2*10 + 1*1
7321 = 7*10^3 + 3*10^2 + 2*10^1 + 1*10^0
Side note: The exponents count down 3,2,1,0. You can think of a similar thing like 7x^3+3x^2+2x+1 and simply replace x with 10.
