Sometimes it seems like people just like to do things “because it’s there.” No real reason, just because. Canon’s X Mark I Mouse seems to have been built under the same impressions, providing us with not only a mouse to use, but a calculator as well.
It’d be handy if you’ve ever found yourself browsing something and need to calculate something really quick. But instead of navigating with too many clicks to the computer calculator, you’re good to go with the X Mark I Mouse in your hands.
Maybe a bit excessive, but at least it doesn’t look too badly designed.