Partial products method : A method for calculating a product of two multi-digit numbers by writing both numbers as a sum of ones, tens, hundreds and so on, then multiplying each pair of terms and finally summing up all the terms. For example $12\cdot 34=(10+2)\cdot(30+4)$ $=10\cdot 30+10\cdot 4+2\cdot 30+2\cdot 4$ $=300+40+60+8=408.$