This method is for multiplying two three digit number.
Let us say the numbers are ABC and DEF.
Write them as shown below.
A B C
D E F
Step 1: C × F
Step 2: (B × F) + (C ×E)
Step 3: (A × F) + (C × D) + (B × E)
Step 4: (A × E) + (B × D)
Step 5: A × D
Let’s take an example to understand this method.
789 × 123
Step 1: 3 × 9 = 27
Step 2: (8×3) + (9×2) = 42 + 2(Carry) = 44
Step 3: (7 × 3) + (1 × 9) + (8 × 2) = 46 + 4(Carry) = 50
Step 4: (7 × 2) + (8 × 1) = 22 + 5(Carry) = 27
Step 5: 7 × 1 = 7 + 2(Carry) =9
So 789 × 123 = 97047