How many 2 digit decimals lie between 2.4 and 2.5 How many 3 digit decimals lie between 2.4 and 2.5 How many 4 digit decimals lie between 2.4 and 2.5?

Answer 1

For the first part:

2.5 - 2.4 = 0.1

2-digit decimals have an interval of 0.01. 0.1 / 0.01 = 10. Since the endpoints are presumably not included ("between"), you have to count one less (10 - 1 = 9). (If you include both endpoints, you would actually have one more: 10 + 1 = 11.)

The reasoning is similar for part 2 and 3.