Hey There
In multiplication you have to know the process of regrouping, which means to take away from tens. Also, you multiply from left to right.
Steps
1. First multiply 5*5=25, the two adds to the product of 5*2
2. Now you have to multiply 5*2=10, now you have to add two because of regrouping, 10+2=12, so you're final answer is 125.
In conlusion, 25*5=125
Hope this helps :)