Let . If is a multiple of 2 and is a multiple of 7, then the number of elements in the smallest subset of containing both and is ____
Answer: 29
Solution
The smallest set containing both and is their union. Between and there are multiples of and multiples of , while the multiples of common to both number . By inclusion-exclusion, .
JEE Main · 2020 · 07 Jan 2020 · Shift 2 · Integer answer