20% of 500 is 100. One fifth of five hundred is one hundred: 500 ÷ 5 = 100. Decimals agree: 0.2 × 500 = 100. Because 500 = 400 + 100, add 20% of 400 (80) and 20% of 100 (20): 80 + 20 = 100. 10% of 500 is 50; doubling gives 100 again. 500 = 10 × 50 and 20% of 50 = 10, so ten tens make 100. On the same base, 25% of 500 is 125 and 30% of 500 is 150—so twenty percent is the clean whole-number fifth below those neighbours.
Read 20% off £500 as “remove £100,” leaving £400 before extras. If someone asks for twenty percent of five hundred—fee, slice, or allocation—the answer is 100, not four hundred. The remainder only matches “after discount” wording.
Compare bases: 20% of 400 is 80 and 20% of 600 is 120, so five hundred’s fifth sits between those at 100. 20% of 450 is 90; adding fifty to the base adds ten to the fifth (90 + 10 = 100). 20% of 250 is 50; doubling the base doubles the fifth (50 × 2 = 100).
Multiply the base by ten: 20% of 5000 is 1000. If a five-hundred-pound subtotal becomes five thousand on the same percentage rule, the slice scales the same way—watch the decimal so you do not report 100 or 10000 by mistake.
If £500 is reduced by 20%, the reduction is £100 and you pay £400 (before other charges).
Change either value below to solve another percentage-of-number question instantly.
Formula used: (percentage ÷ 100) × number
Step 1: Convert 20% → 0.2.
Step 2: Multiply: 0.2 × 500 = 100.
Full formula: (20 ÷ 100) × 500 = 100
Fifth shortcut: 500 ÷ 5 = 100. Split: 20% of 400 + 20% of 100 = 80 + 20 = 100. Or 300 + 200: 60 + 40 = 100.
Five hundred is 50 × 10, so 10% = 50 and doubling lands on 100 on the nose.
The base is exactly 5 × 100. Since 20% of 100 is 20, five copies line up as 20 × 5 = 100—an easy structural check for any total built from hundreds.
Fastest: 500 ÷ 5 = 100.
From 25% of 500 = 125, subtract 5% of 500 = 25 to land on one hundred—useful if quarters come first mentally.
Example 1: Twenty percent off a £500 fee
The markdown is £100 and you pay £400 if nothing else stacks.
Example 2: Five-hundred-unit batch
If a 20% quality hold applies, 100 units are ring-fenced and 400 are free to ship under a strict rule.
Example 3: Budget line
Allocating 20% of a £500 sub-budget means £100 for that line and £400 notionally elsewhere—not the other way round unless the wording says “after discount.”
Example 4: Tenfold check
20% of 5000 is 1000. If you see 100 or 10000 on the scaled row, revisit the percent-to-decimal step.
20% of 500 is 100.
Multiply 500 by 0.2, divide 500 by 5, or double 10% of 500 (50 → 100).
20% off 500 is a reduction of 100, leaving 400.