Speed Up - Calculations

Multiplication of 2 digit no. 

87 x 92
 Step 1: Multiply 8 with 9 = 72
 Step 2: Cross multiply 8 with 2 and 7 with 9 and add the result = 16+63 = 79
 Step 3: Multiply 2 with 7 = 14
 Step 4: Put them in the order give below

    87
 x 92
~~~~~
72| 79| 14

Take 4 of 14 as the extreme right digit and carry 1 to 79 to make it 80. Put 0 as a second digit and carry 8 to 72 to make it 80 hence the answer is   8004

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