Question 1195198: Consider the numbers 0,2,5,6. How many two-digit numbers can be formed without repetition, such that.
a): all are even?
b): all are greater than 60?
Answer by ikleyn(52781)   (Show Source):
You can put this solution on YOUR website! .
Consider the numbers 0,2,5,6. How many two-digit numbers can be formed without repetition, such that.
a) all are even?
b) all are greater than 60?
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(a) all are even ?
Even number must have last digit 0, or 2, or 6.
If the last digit is 0, then the first digit can be any of 2, 5, 6. It gives 3 numbers.
If the last digit is 2, then the first digit can be 5 or 6, giving 2 numbers.
If the last digit is 6, then the first digit can be 2 or 5, giving 2 numbers.
In all, there are 3 + 2 + 2 = 7 two-digit even numbers of this kind.
(b) all are greater than 60 ?
There are only two such numbers. They are 62 and 65.
Solved.
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