I got a basic math book from the library to sharpen my math skillZ and I noticed I keep getting one problem wrong. Estimate using compatible numbers division 321 ÷ 19 . Now me and someone else keep getting the wrong answer but our answer is the same so I wanted to see what some other peeps would get on this. Is it us or the book? I'll tell you the answer and what we get after I get some replies. It's eating at me something this basic is causing me trouble.