maths

esmehan:

what is the total number of the two-digit prime numbers that have a 3 as a unit

Hi esmehan,
I am wondering why you can't do this for yourself.?
Do you mean that you want 3 in the unit column, so do you mean that is must have a 3 in either place?

anyway, you only need to think about
3,13,23,33,43,53,63,73,83,93 and decide it they are prime and then count them.
It it is in either place you will need to look at all the 30 somethings as well.

you need to find all 2 digit #s with a 3 first


13; 23; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 43; 53; 63; 73; 83; 93
now determine if it is prime or not
13 prime
23 prime
30 not
31 prime
32 not
33 not
34 not
35 not
36 not
37 prime
38 not
39 not
43 prime
53 prime
63 not
73 prime
83 prime
93 not
8 2 digit #s with a 3 are prime