Brain Teasers
Less than 3 Million
How many 7 digit EVEN numbers less than 3,000,000 can be formed using the digits, 1, 2, 2, 3, 5, 5, and 6?
Hint
You must account for the identical digits to make sure you don't double count.Answer
If the digit:1 is first and 2 is last, there are 60 ways to form a 7 digit even number less than 3,000,000.
1 is first and 6 is last, there are 30 ways to form a 7 digit even number less than 3,000,000.
2 is first and 6 is last, there are 60 ways to form a 7 digit even number less than 3,000,000.
2 is first and 2 is last, there are 60 ways to form a 7 digit even number less than 3,000,000.
So, adding up all the different combinations that can be formed we get:
60+30+60+60 = 210.
In total, 210 ways to form a 7 digit even number less than 3,000,000 using the digits 1, 2, 2, 3, 5, 5, and 6.
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