Hi Jean,

If you are choosing 5 numbers from 59 numbers and you know that one of them is 23 then you have 58 choices for the remaining 4 numbers. The number of ways of choosing 4 things from 58 things is called 58 choose 4, written $\large 58 \choose 4$ and calculated by

\[\frac{58 \times 57 \times 56 \times 55}{4 \times 3 \times 2 \times 1}\]

Google will do the arithmetic for you. If you type 58 choose 4 into the Google search window the response is 58 choose 4 = 424 270.

Penny