How many numbers between 0 and 1370 have a prime tens digit and a prime units digit?
Pick one.
A) 204
B) 212
C) 220
D) 228
E) 236
From 1-9 there are 4 prime numbers {2, 3, 5, 7}. The 10s and 1s of the number must be made with these numbers. The total number of combinations is  4*4= 
<gadget id="calculator"> 4*4</gadget>
<output>16</output>
16. Thus every set of 100 consecutive positive integers has 16 such numbers.   From 0 to 1300, there  16*13= 
<gadget id="calculator"> 16*13</gadget>
<output>208</output>
208 such numbers.   From 1301 to 1370, the 10s units can only use 3 numbers {2, 3, 5}. 3*4=12.   The total number is then  208+12= 
<gadget id="calculator"> 208+12</gadget>
<output>220</output>
220   The answer is 220.
<result>C</result>
How many numbers between 0 and 1370 have a prime tens digit and a prime units digit?