Multiplication is plussing something a bunch of times for example 12*3 is 12+12+12. but it gets more complicated every time. These are some of my methods for 2 digits times 2 digits.

1 Area method where you do one side of one factor and the other side is the other factor. You multiply the factors on one side by the factors on the other side. You then add all of the partial products to find the one big product.

2 Partial products method. Say you are multiplying 25*39. first you multiply 5*9 you put the answer underneath . Then you multiply 20*9 and put the answer underneath as well. then you multiply 30*5 and put the answer underneath. Finally you multiply 50*30 and put the answer underneath. You add all the answers up and you have your big total.                                                                                                                                                                                                                                                                       .
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          z 3 fast method. Say you’re multiplying 25 *39. You do 5*9, put the 4 on top and the 5 on the bottom. then you do 20*9+45 and that’s you’re  first   subtotal. Then you cross out the 9 and put a 0 underneath. Then you multiply 30*5. Finally you multiply 30*20 plus 150 and then you add your subtotals up and you have the product.