What is 15% of 40? 6 15% of 40 Copy 15% of 40 = 6. Formula UsedResult = (15 ÷ 100) × 40 = 6 Frequently Asked Questions What is 15% of 40?6. (15 ÷ 100) × 40 = 6.How to calculate 15%?Multiply by 0.15 (or multiply by 15 then divide by 100).