Tables

At a glance 10 rules

1. 1Labels and units firstRead the row and column labels, the units (lakh, thousand, quintal) and any footnote before adding; most slips are the right sum on the wrong row.
2. 2Missing cellsA missing cell is its row or column total minus the cells you have; if only a share or growth of the total is given, write that equation for the cell.
3. 3Back to old value$\text{old} = \dfrac{\text{new}}{1 + \dfrac{g}{100}}$$g = \%\ \text{change; a fall is negative}$
4. 4Combine columns per row$\text{value} = \text{area} \times \text{yield} \times \text{price}$$\text{convert first: } 1\ \text{tonne} = 10\ \text{quintals}$
5. 5Rate beats sizeFor 'best', 'most efficient' or 'fastest growing', compare the rate the question names (per hour, per employee, rise over the old value), never the biggest raw number.
6. 6Points vs percent$\text{points} = \text{new rate} - \text{old rate}$$\%\ \text{change} = \tfrac{\text{points}}{\text{old rate}} \times 100$
7. 7Growth of a total$g = \dfrac{\sum \text{old}_i \times g_i}{\sum \text{old}_i}$$g_i = \text{growth of row } i$
8. 8Change per change$\dfrac{\Delta y}{\Delta x} = \dfrac{y_t - y_{t-1}}{x_t - x_{t-1}}$$x, y = \text{columns},\ t = \text{this year}$
9. 9Several conditionsApply the condition that knocks out the most rows first, then test only the survivors; 'at least' includes the boundary value.
10. 10True or false statementsTest the statement with the least arithmetic first; each verdict deletes answer options, and the last statement often needs no check.