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Homework answers / question archive / Five digit numbers are made using the numbers 0 to 7
Five digit numbers are made using the numbers 0 to 7. Determine number of even numbers that can be
made if each digit can only be used once. [2]
3,720 ways
Step-by-step explanation
Given: numbers 0 to 7 = 0, 1, 2, 3, 4, 5, 6, 7 = total of 8 numbers
Even numbers are 0, 2, 4, 6
Any 5-digit number that has the last digit of 0, 2, 4 and 6 are made of even numbers, as it is divisible by 2.
First, we choose 0 for the last digit.
That's 1 way. Choose the first digit 7 ways (excluding 0).
Choose the 2nd digit 6 ways.
Choose the 3rd digit 5 ways.
Choose the 4th digit 4 ways.
That's 7 * 6 * 5 * 4 * 1 = 840 ways
Second, we choose 2,4 or 6 being the last digit.
That's 3 ways. Choose the first digit 6 ways (0 can't be a first digit).
Choose the 2nd digit 6 ways.
Choose the 3rd digit 5 ways.
Choose the 4th digit 4 ways.
That's 6 * 6 * 5 * 4 * 4 = 2,880 ways
Thus, we have the
total of even numbers that can be made = 840 + 2,880 = 3,720 ways