How many numbers between 0 and 1670 have a prime tens digit and a prime units digit?
Options.
A) 268	B) 272	C) 202	D) 112	E) 262
There are 4 single digit prime numbers: 2, 3, 5 and 7. Hence, last two digits (tens and units) can take  4*4= 
<gadget id="calculator"> 4*4</gadget>
<output>16</output>
16 different values: 22, 23, ..., 77.   So, in each hundred there are 16 such numbers. In 17 hundreds there will be 17*16= 
<gadget id="calculator">17*16</gadget>
<output>272</output>
272 such numbers, but 4 out of them will be more than 1670, namely: 1672, 1673, 1675 and 1677. Which means that there are  272-4= 
<gadget id="calculator"> 272-4</gadget>
<output>268</output>
268 numbers between 0 and 1670 which have a prime tens digit and a prime units digit.   268nswer: 268.
<result>A</result>
How many numbers between 0 and 1670 have a prime tens digit and a prime units digit?