so, something that multiplies itself and you get 169, and adds itself and gives 26 hmmmmmm.
a = the number.
well... we can use either... let's use both cases
a*a = 169 ---> a² = 169 ---> a = √(169) ---> a = 13
a + a = 26 ---> 2a = 26 ---> a = 26/2 ---> a = 13