
I keep getting a different result than from an online calculator. - http://www.wolframalpha.com/input/?i=353+to+binary
What have I done wrong?

I keep getting a different result than from an online calculator. - http://www.wolframalpha.com/input/?i=353+to+binary
What have I done wrong?
You are almost at the end of your binary conversion. Just add the last 1 (the quotient $2/2$) and read it backwards. Therfore you obtain $$353=(101100001)_2$$
Just write the successive quotients
$$353,176,88,44,22,11,5,2,1$$ and assign the binary digits $0/1$ to even/odd, from least significant to most significant.
$$101100001.$$