Grandma's Age
You went to visit your grandma once again on her birthday, this time with your family. As you walk up to her to give her a hug, she says, "I've just noticed something. You like math, right? Right. Now, I have always been 45 year older than your dad, but today, the two prime digits in my age are reverse the two digits in your dad's age."
"That's right, mom." your dad says.
After thinking for a while, can you tell your grandma how old she's turning?
The answer is 72.
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.
1 solution
(10x + y) - (10y + x) = 45 = 9x-9y. 5 = x - y, and x and y are prime. x = 7, y = 2. 72