Something with number formatting

When I type a few numbers at the beggining of my message, and then add a dot, and then add a word, the numbers change to 1000000000. I tried it a few more times with my friend.

It doesn't work when I don't add any words after the numbers. 

It changes the numbers when I write a number with more than 10 digits.

This only happens when I write a number with more than 10 digits with a dot and add a word afterward. It doesn't happen if I don't add any words after the numbers. I'm not sure if this is on purpose, but I wanted to bring it to your attention. Thank you.