20

Just divide the percentage by 100 and multiply it with the number (so 0,025 x 800 = 20)

2.5% = 800

so 100%= 800*100/2.5 = 32,000

Number is 32,000

Answer = 20

ie: 800 divide by 100 = 8 (1%)

8 multiplied by 2.5 = 20 (2.5%)