Not understand the test case

#1

please elaborate the test case

#2

Hi

Number of numbers divisible by prime numbers less than 20 between 1 to n

Prime numbers less than 20 are : 2 3 5 7 11 13 17 19
test cases:

for n = 5

total numbers are: 4 ( 2, 3,4 5 these are divisible )

n= 10
total numbers are: 9 ( 2,3,4,5,6,8,9,10,12)

similar check for others