i love the random display - one of the best features of dA - it just showed me this one - my daughter(9) is also looking and when i told her that these came "from the deep oceans of mathematics) she said - "the left one is multiplicate and the right one is subtract"...
yes, we didn't see it because we are not "eagle eye", that's what i call her sometimes... she is an amazing watcher and animal track reader - she even spots horse tracks on grass where i don't see nothing - until she shows me, haha...
Of course it is, why didn't we see it?