Summation & Totals
Adding values to compute totals, subtotals, or aggregates from data tables.
Practice This ConceptUnderstanding Summation & Totals
Many EPSO questions require computing a total before you can calculate a percentage or average. The total is not always given — you must add the rows yourself. This is simple arithmetic, but under time pressure with 4-6 rows of numbers, addition errors are common.
Formula
$total = \sum_{i=1}^{n} x_i$
Key Rules
- Always verify that the parts add up to the total if both are given
- If the total is missing, add all parts before computing percentages
- Watch for subtotals vs grand totals — EPSO tables sometimes include both
- Units matter: you cannot add millions and billions without converting first
Examples in Action
1
54.8 + 53.9 + 18.7 + 13.2
=
140.6
EU budget total from 4 sectors
2
32,754 + 32,894 + 19,542 + 37,817
=
123,007
Total electricity from 4 sources
3
67 + 83
=
150
Total population weight for weighted average
Common Errors
- Missing a row when adding (especially in tables with 6+ rows)
- Including a subtotal row in the sum (double counting)
- Adding numbers with different units
Pro Tip
When adding 4+ numbers under time pressure, add pairs first: (54.8+13.2)=68 + (53.9+18.7)=72.6 → total 140.6. Pairing round numbers reduces errors.