You tin swap the percent in addition to the amount: 16% of £25 is hard to calculate inward your head, only 25% of £16 is just the same amount.
So if you lot desire to rapidly live on out 16% of £25 without a calculator, uncovering 25% of £16 instead (ie split £16 past times 4). Simple!
Think nigh why this works.
Source: www.aperiodical.com
