find the number whose seventh part exceeds its eighth part by 1

Let the number be 'x'

seventh part of the number = x/7
eighth part of the number = x/8
difference = 1

let us form the equation

x_​/7 - x/8 = 1

x*8/7*8 - x*7/8*7 = 1

8x/56 - 7x/56 = 1

x/56 = 1

x = 56


​hence, the number is 56.