What Is 15% of 80? (And the Pattern Behind It)

The answer

15% of 80 is 12.

Three ways to get there

Method 1: decimal

15% = 0.15
0.15 × 80 = 12

Method 2: fraction

15/100 × 80 = (15 × 80) / 100 = 1200 / 100 = 12

Method 3: 10% + 5%

10% of 80 = 8
5% of 80 = 4 (half of 10%)
15% = 8 + 4 = 12

The 15% shortcut

Method 3 generalizes to any 15% calculation:

1. Take 10% (move the decimal one place left).
2. Halve that to get 5%.
3. Add the two.

Try it with 15% of $64.50:

• 10% = $6.45
• 5% = $3.225
• 15% = $9.675 ≈ $9.68

This is why 15% is the most-used tip percentage in countries where tipping is optional — it’s the easiest non-round percentage to compute at the table.

Related calculations

• 20% of 80 = 16 (double the 10%)
• 25% of 80 = 20 (quarter)
• 50% of 80 = 40 (half)
• 5% of 80 = 4 (half of 10%)
• 1% of 80 = 0.8 (move decimal twice)