505 divided by one equals the missing number.
To find the missing number or the quotient, we need to divide 505 by one. The divisor in this question is number one. The divisor tells us that we need to share our number into one equal group. In other words, if we had 505 objects and we shared them all into one equal group, how many objects would that be in the group? There would be 505. So 505 divided by one equals 505.
You may have noticed that the dividend, 505 or the number we started with, is the same as the quotient or the answer. This is because when we divide a number by one, the answer is always the same as the dividend.