What is 40% of 40? 16 40% of 40 Copy 40% of 40 = 16. Formula UsedResult = (40 ÷ 100) × 40 = 16 Frequently Asked Questions What is 40% of 40?16. (40 ÷ 100) × 40 = 16.How to calculate 40%?Multiply by 0.4 (or multiply by 40 then divide by 100).