how many digits are there in the repeating block for the decimal equivalent of 3/7

$${\frac{{\mathtt{3}}}{{\mathtt{7}}}} = {\mathtt{0.428\: \!571\: \!428\: \!571\: \!428\: \!6}}$$

There you go - you can count them :)

You can use the calculator at this site to figure this out.

For any problem divided by n, there cannot be more than n - 1 digits in the repeating block; thus, the answer to this problem cannot be more than 6.

I didn't know that gino - thanks.