Im confused on this test

Question

1.which of the following is greater than 4.3×10^9
A.)2.1×10^9
B.)3.2×10^9
C.)5.3×10^9
D.)7.4×10^8

If possible I need help with all questions

Answer 1

First, you have to get them all to the same power of 10.
10^8 = 0.1 * 10^9, so
7.4x10^8 = 0.74x10^9

Now, which number is greater than 4.3?