SAT MATH question !!!

<p>How many positive integrals less than 1000 are not divisible by 3 ?</p>

<p>right answer 666</p>

<p>To find out the number of positive integers less than 1000 that ARE divisible by 3, divide 999 by 3. The result is 333. Therefore, there are 1000-333=666 numbers that are NOT divisible by 3.</p>

<p>What might help you identify this question if your given bizzare numbers and much higher than 1000. </p>

<p>If the number has its digits add to a multiple of 3,then its divisable by 3;</p>


<p>18: 1 + 8 = 9 its divisable by 3;</p>

<p>In this example we see greatest number divisible by 3 is:</p>

<p>999 = 9 + 9 + 9 = 27,which is divisible by 3.</p>

<p>999 / 3 = 333;</p>

<p>1000 - 333 = 666 NOT Divisible by 3.</p>

<p>Hope that helps.</p>

<p>There is no need to put that much thought into this. Just divide 1000 by 3 and take the integer part (ignore anything after the decimal point). In other words, it is not necessary to find a number divisible by 3 before performing the division. </p>

<p>So 1000/3 ~ 333.33333. So just take 333 and subtract it from 1000.</p>


<p>So there are 667 integers less than 1000 that are NOT divisible by 3.</p>

<p>Important remark: After performing the division we are NOT rounding. We are DELETING everything after the decimal point.</p>