Thank you for reporting, we will resolve it shortly
Q.
The number of natural numbers less than 400 that are not divisible by 17 or 23 is
Sequences and Series
Solution:
divisible by 17 and less than $400$
$17, 34, 51, ........ 391 (23)$
divisible by 23 but less than $400$
$23, 46, 69,.........391 (17)$
divisible by both
$391 (1)$
divisible by 17 or $23 = 23 + 17 - 1 = 39$
not divisible by 17 or 23 and $< 400$
$= 399 - 39 = 360 $