Base Method

This is very suitable when numbers are close to a base like 10, 100, 1000 or so on. Let's take an example:
106 × 108

Here the base is 100 and the 'surplus' is 6 and 8 for the two numbers. The answer will be found in two parts, the right-hand should have only two digits (because base is 100) and will be the product of the surpluses. Thus, the right-hand part will be 6 × 8, i.e. 48. The left-hand part will be one multiplicand plus the surplus of the other multiplicand. The left part of the answer in this case will be 106 + 8 or for that matter 108 + 6 i.e. 114. The answer is 11448.

12 X 14.

10 would the most suitable base. In the current example, the surplus numbers are +2 and +4.

If 8x7 were to be performed and base of 10 were chosen, then -2 and -3 would have been the deficit numbers.