Its easy
Number Theory
Level
1
A two-digit number ab and its reversal ba are both prime. For example, 13 and 31 are both prime. What is the largest possible sum of these two numbers ab and ba?
The answer is 176.
This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
The largest two-digit prime number is 97, and its reverse is 79. So, the sum is 176