One of my best math problems

 My father, Morris Sherman,  died in 1989 -- 85 days after his 74th birthday. He died in less than one day from internal bleeding caused by an aneurism. He was active and healthy and enjoying life until he had one bad day. There are worse ways for a life to end.

During my father's last four years, I was in a detour in my career. Music programs were shrinking in NYC public high schools. To stabilize my employment, I did what I had to do to get certified and began a 12 year long exile from music education as a math teacher. 

My father began his life as a smart little guy who started high school when he was 12 years old because his elementary school skipped him ahead a grade two times. He was a bit of a numbers nerd. I entertained him with birthday cards I made up that pointed out some interesting properties of the number of the birthday he was reaching each year. 

On Morris' 73rd birthday, my card pointed out that 73 was part of a twin prime, and very likely to be the last twin prime number birthday he would live to see. The next twin primes after 71-73 are 101-103. 

Brave reader, indulge me now in digression. 101, 103, 107, and 109 are all prime numbers. This is the first occurrence of a double-twin prime decade. A double-twin prime decade is one in which consecutive odd numbers ending with 1.3. 7. and 9 are all prime numbers. They are exceedingly rare. The next five double twin prime decades that occur after the first one begin with 191, 821, 1871, 2081, and 5651.

We will now proceed with the subject of this essay. Here is the math problem I wrote on the birthday card for my father's 74th birthday:

Pretty nifty. However, what I especially like about this problem is the first sentence. Without the first sentence, 47 would be another possible answer.

                                      (4 + 7)^2  - 74                      (4-7)^3 + 74

                                       11^2 - 74                             (-3)^3  + 74

                                       121 - 74 = 47                       -27 + 74 = 47

You see? 47 works BUT anyone who turned  47 in 1989 was born in 1942 and thus could not be a World War II veteran. Therefore the first sentence was necessary to make 74 the only possible answer.