Approximating the product of two real numbers Let $a,b$ two positive real numbers. For example I want to calculate approximate value of $45.11\times 67.89$ only to 2 decimal places. Note that any calculators or other such devices aren't allowed. Also suppose I want to calculate $\frac{11789}{234558}$ only approximately to 2 decimal places then how to do it? One might ask why do I want to randomly calculate multiplication and division. Actually that isn't the case. There's an exam which I will be taking which has one of the sections as $\text{Data Interpretation}$. In this section there are problems related to the annual turnover ,profits of a company and many such things . Say that its given in the form of a pie chart the quarterly sales of a company for a certain year and we are asked to find the percentage increase /decrease in two consecutive quarters thus the question to quickly estimate the approximate value or if not that atleast giving a small range within which the value may fall. Any quick methods /suggestions will be appreciated! here I have provided one of the sample questions . What I am asking is a generalized method like using percentage(mostly for division).

It's $$(45+0.11)(68-0.11)=3060+23\cdot0.11-0.0121=$$
$$=3062.53-0.0121=3062.5179\approx3062.52$$
