<p>From 1 to 1000 how many numbers have at least one zero.</p>
<p>ETC, like those type. Is there a easy way to solve it??</p>
<p>Find the number of #'s with no zeros (a much easier problem). Subtract that from 1000. Kind of like a complementary counting problem.</p>
<p>How about it finding out at least 2 zeros?</p>
<p>The leftmost digit is not zero, so we are considering 3 digit numbers and 1000. Let’s skip 1000 for the moment and focus on the 3 digit numbers.</p>
<p>The first (leftmost) digit cannot be zero. After all the numbers are 3 digits. So the tens digit AND the ones digit must be zero – i.e. 9 3 digit numbers fit the bill (100, 200, 300, …, 900). Then there’s 1000. The 10th number.</p>
<p>Yeah, “at least two zeros” is easy. 100, 200, …, 900, 1000.</p>
<p>thank you guys!!</p>
<p>:D</p>