What numerical expression for 31 increased by 14?

"increased by" means something is added. So,

31 + 14

To obtain the numerical expression for 31 increased by 14, you simply need to add the two numbers together.

So the expression would be:
31 + 14

To find the answer, you can perform the addition:

31 + 14 = 45

Therefore, the numerical expression for 31 increased by 14 is 45.