Sequences & Series
Counting 3-digit numbers (combinatorics — misplaced)
nta_pyq_2023_jan
Grade 11
Question:
The number of 3-digit numbers, that are divisible by either 2 or 3 but not divisible by 7 is ______.
Step-by-Step Solution
Key Concept: Use inclusion-exclusion: count 3-digit numbers divisible by 2 or 3, then subtract those also divisible by 7.
Answer = 514.
Correct Answer: 514