Question 1209367
<br>
{{{3+4+5+8=20}}}
{{{13+14+15+18=60}}}
{{{23+24+25+28=100}}}
...
{{{993+994+995+998=3980}}}<br>
The sum of all of these gives us an arithmetic sequence of 100 terms with first term 20 and last term 3980.<br>
Using the informal formula for the sum of the terms of an arithmetic sequence<br>
Sum = (# of terms) * (average of first and last)<br>
gives us<br>
{{{100*(20+3980)/2=100(4000/2)=100(2000)=200000}}}<br>
ANSWER: 200,000<br>