How many 4 digits numbers divisible by 5 can be formed with digits 0,1,2,3,4,5,6 and 6
options:
a) $220$
b) $249$
c) $432$
d) $216$
MyApproach:
To form a 4 digit number divisible by 5 using given numbers
I make cases here:
Unit Digit is $0$ and other $3$ numbers can be formed in $7$ . $6$ . $5$=$210$
Unit Digit is $5$ and other $3$ numbers can be formed in $6$ . $6$ . $5$=$180$
Therefore,the required number is $390$
Is my approach right?Please correct me if I am wrong?
Best Answer
Your approach is fine except for you are missing the repeated digit. Here is a lazy solution:
Imagine we only have $0,1,2,3,4,5,6$, then your sums become:
Therefore there are at least $220$ and at most $390$ solutions, therefore the answer is b ($249$).