7+5+3=?

Do you know the answer to this question?

7 + 5 + 3 = A Japanese holiday to celebrate the health of children.
We write it 七五三(literally meaning seven five three).
Girls celebrate twice at the age of 3 and 7, and boys celebrate once at the age of 5. It is pronounced "SHICHIGOSAN"(*) and is on November 15th, meaning yesterday. You must have seen many girls and boys in mini kimonos running around yesterday. It is said to have been a custome around the KANTO area but now a national holiday. Orinigally people celebrated that their children grew up well when the mortality rate was higher in the older days, and there are many variations throughout Japan, combining other local customs. The rate of having atopic babies is said to be rising these days. It is time we should hault taking childrens' health for granted.

(*)The pronounciation can be HICHIGOSAN as well. I come from Tokyo, so tend to pronounce HI as SHI. Both are correct, but if you want to make yourself hear like a EDOKKO (Edo cool kid?) try out with "SHI".