What is the best approach to select multiple values from a list of values in ascending order?

I have a section in a webapp where the user can select from a series of values, which are displayed in ascending order (to perform an unspecified function). The user can select among any of these values. The screenshot below is an example of an acceptable input.

Is there a better way to display these values? At first glance, it doesn't really convey that the values are in ascending order.

i.e.

• Should I arrange them from left to right instead of top down?
• Should I put all options in a single horizontal or vertical line?
• Is there a better solution than using checkboxes as shown below?