Confused about national income in economics? You’re not alone. National income is calculated using the formula C I G (X - M). That means consumption, investment, government spending, exports minus imports. Knowing what each part of this formula represents is essential for economics exams. One key exam tip to remember is that GNP is not used as an accurate measure of Ireland’s national income, so always stick to the correct formula when answering questions. Mastering national income calculations