Answer: 5x10^-2, 3x10^-4, 2x10^5, 7x10^5.
Step-by-step explanation: To order the numbers 7x10^5, 5x10^-2, 2x10^5, 3x10^-4 from least to greatest, you need to compare the values of the numbers.
The first step is to compare the base numbers (the numbers before the "x10" part):
7 is greater than 5, which is greater than 2, which is greater than 3.
The second step is to compare the exponent values (the numbers after the "x10" part):
5 is greater than -2, which is greater than 5, which is greater than -4.
Based on these comparisons, the order of the numbers from least to greatest is:
5x10^-2, 3x10^-4, 2x10^5, 7x10^5.