Numerical Data Interpretation (Tables and Graphs)
Data interpretation questions present a table, bar chart, line graph, or pie chart and ask you to extract, compare, or compute from it. The skills are: reading the correct row and column, respecting units and scale (thousands, millions, percentages), and computing differences, totals, averages, and percentage changes from the figures shown.
Approach every question by first identifying exactly what is being asked, then locating only the data needed. Do not read the whole table - target the cells. Check axis labels and legends carefully; a graph's vertical axis may not start at zero, exaggerating differences. In pie charts, sectors represent proportions of a total, so convert angles or percentages into absolute values only when the total is known.
Traps: mixing units (a column in thousands beside one in units); confusing percentage points with percentages; reading the wrong year or category under time pressure; and averaging averages, which is usually wrong. Rounding mid-calculation can also shift you to a neighbouring distractor.
Worked example: if sales were 40 (thousands) in Year 1 and 50 (thousands) in Year 2, the increase is 10,000 units, or 25% - not 10%. Rule of thumb: annotate units beside every figure you extract before computing.