>>105763177
Heres a couple of ways a human might do it:

A: The Low IQ Summer
25 * 25
=> (5 + .. ) 25
=> (125 + .. )
=> (100 + ..) + (25 + ...)
=> 500 + 125
== 625

B: The Chad 100 modulo
25 * 25
=> 25 * 24 + 25
=> 25 * 4 * 6 + 25
=> 100 * 6 + 25
== 625

C: The Schizo
25 * 25
5 * 5 * 5 * 5
25 * 5 * 5
125 * 5
625