Find the smallest nine-digit number that is not divisible by five.
The nine-digit numbers range from 100000000 to 999999999. We are looking for the smallest one of these that is not divisible by five. Any whole number, or integer, is divisible by five if its units digit is a five or zero. Let’s consider the smallest nine-digit number. 100000000 has a zero in the units column. This means that it is divisible by five. Therefore, it is not the correct answer.
The next smallest nine-digit number is 100000001. This number has a one in the units column. We can, therefore, say that it is not divisible by five. Any whole number that does not end in a five or zero will not be divisible by five. The smallest nine-digit number that is not divisible by five is 100000001.