4. Which of the following numbers is not an integer?
A $\frac{2011}{1}$
B $\frac{2012}{2}$
C $\frac{2013}{3}$
D $\frac{2014}{4}$
E $\frac{2015}{5}$
4. D The numbers in options A, B and E are clearly integers. In option C, $2+0+1+3$ $=6$ so, using the divisibility rule for divisibility by $3, \frac{2013}{3}$ is also an integer. However, while 2000 is divisible by 4,14 is not so only $\frac{2014}{4}$ is not an integer.