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How many positive integers less than 500 are the product of exactly
two distinct (meaning different) primes, each of which is greater than 10?

Guest Mar 5, 2015

Best Answer 

 #1
avatar+18829 
+5

How many positive integers less than 500 are the product of exactly
two distinct (meaning different) primes, each of which is greater than 10 ?

 

$$\small{\text{
$
\begin{array}{r|rcl|r}
\hline
n & p_1 & & p_2 & p_1\cdot p_2 \\
\hline
1 & 11 & \cdot & 13 & = 143 \\
2 & 11 & \cdot & 17 & = 187 \\
3 & 11 & \cdot & 19 & = 209 \\
4 & 11 & \cdot & 23 & = 253 \\
5 & 11 & \cdot & 29 & = 319 \\
6 & 11 & \cdot & 31 & = 341 \\
7 & 11 & \cdot & 37 & = 407 \\
8 & 11 & \cdot & 41& = 451 \\
9 & 11 & \cdot & 43 & = 473 \\
10 & 13 & \cdot & 17 & = 221 \\
11 & 13 & \cdot & 19 & = 247 \\
12 & 13 & \cdot & 23 & = 299 \\
13 & 13 & \cdot & 29& = 377 \\
14 & 13 & \cdot & 31 & = 403 \\
15 & 13 & \cdot & 37 & = 481 \\
16 & 17 & \cdot & 19 & = 323 \\
17 & 17 & \cdot & 23 & = 391 \\
18 & 17 & \cdot & 29 & = 493 \\
19 & 19 & \cdot & 23 & = 437 \\
\hline
\end{array}
$
}}$$

heureka  Mar 5, 2015
Sort: 

1+0 Answers

 #1
avatar+18829 
+5
Best Answer

How many positive integers less than 500 are the product of exactly
two distinct (meaning different) primes, each of which is greater than 10 ?

 

$$\small{\text{
$
\begin{array}{r|rcl|r}
\hline
n & p_1 & & p_2 & p_1\cdot p_2 \\
\hline
1 & 11 & \cdot & 13 & = 143 \\
2 & 11 & \cdot & 17 & = 187 \\
3 & 11 & \cdot & 19 & = 209 \\
4 & 11 & \cdot & 23 & = 253 \\
5 & 11 & \cdot & 29 & = 319 \\
6 & 11 & \cdot & 31 & = 341 \\
7 & 11 & \cdot & 37 & = 407 \\
8 & 11 & \cdot & 41& = 451 \\
9 & 11 & \cdot & 43 & = 473 \\
10 & 13 & \cdot & 17 & = 221 \\
11 & 13 & \cdot & 19 & = 247 \\
12 & 13 & \cdot & 23 & = 299 \\
13 & 13 & \cdot & 29& = 377 \\
14 & 13 & \cdot & 31 & = 403 \\
15 & 13 & \cdot & 37 & = 481 \\
16 & 17 & \cdot & 19 & = 323 \\
17 & 17 & \cdot & 23 & = 391 \\
18 & 17 & \cdot & 29 & = 493 \\
19 & 19 & \cdot & 23 & = 437 \\
\hline
\end{array}
$
}}$$

heureka  Mar 5, 2015

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