Example  1 : 42*48 = 2016

Step 1 : The numbers are partially complementary if the sum of their unit place digits is 10 and the tens place digits are same i.e. 42*48

Step 2 : First 2 digits will be 4*5 = 20 (i.e. multiply the first digit with immediate higher number )

Step 3 : Last 2 digits of the result can be obtained by multiplying their unit place digits i.e..2*8 = 16

Step 4 : 2016 (It’s the final answer)

 

Please try:

1. 53*57
2. 36*34
3. 63*67