Which of the following sentences is true? a. 6.3 is less than 6.2. b. 6.8 is greater than 6.5. c. 6.6 is less than 6.0. d. 6.4 is greater than 6.9.

b. 6.8 is greater than 6.5.    
This is the true sentence

The answer is b. 6.8 is greater than 6.5. It's very easy to figure out. You look at the first numbers and the one that has the greater first number is the highest one. But if both of the first numbers are the same, then you move on to the next digit until you find the greater one. And that will be the greatest one. You do the same thing even if your comparing more than two numbers.