have one Pi

1-> 9 have 9 digits

10->99 have 180 digits because 99-10+1=90 numbers and one numbers have a two digits :90.2=180

100 have 3 digits

total digits is : 9 + 180 + 3 = 192 digits

divisible by 15 = 0

divisible by 7 = 0

3 giờ 36 phút

=36 phút

=3 giờ