Add a count to an SQL select statement

I would like to make a select statement, using a select distinct, and include a count in each record returned.

For example, for the dataset below, I would like the record to return only 1 instance of the "order number" and a count of how many different ones there are.

Can someone help with this? Thank you.

I would like the return to show this, from the dataset below it.

Query return:
Order Number | Count
1234567                 3
7896548                 1

Data set:
ID | Order Number
1     1234567                    
2     1234567
3     1234567
4     7896548