+28 Syd chooses two different primes, and multiplies them. If both primes are greater than 4, and the resulting product is less than 200, then how many different products could Syd have ended up with?
+399 The lowest prime that satisfies this is 5, because 5 is right after 4.
To find the highest, do 200/5 = 40, and round down which is 37.
There are a total of 10 primes between these 2:
5, 7, 11, 13, 17, 19, 23, 29, 31, 37
Lets count the total number (excluding those that have already been counted)
Groups with 5: 7, 11, 13, 17, 19, 23, 29, 31, 37 total : 9
Groups with 7: 11, 13, 17, 19, 23 total : 5
Groups with 11: 13, 17 total : 2
No more after this ~
There are a total of 9 + 5 + 2 = 16 total products.
