Alex wants to write the number 100,000 using a base of 10 and an exponent what number should we use as an exponent

The number 100,000 (one hundred thousand) has five zeros. So 5 should be the exponent over 10.

In other words, 10^5 = 100,000



A more formal way to find the exponent is to use logs. Specifically use log base 10. Many calculators use base 10 by default. 

Type in "log(100000)" without quotes and the result will be 5

So log(100000) = 5 helping confirm that 10^5 = 100000.