How many prime numbers are between 20 and 70?

Answer 1

Count for yourself. Here are all prime numbers from 1 to 100: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97.

Answer 2

There are 11 prime numbers between 20 and 70. To find them, you can list out the numbers between 20 and 70 and then eliminate all the composite numbers by checking if they are divisible by any number other than 1 and themselves. The prime numbers between 20 and 70 are 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, and 67.