How many times will the digit '1' appear if we write all whole numbers from 1 to 99?

Can someone check my answer? you : )

The length and width of a rectangle are consecutive even integers the area of the rectangle is 120 squares units what are the length and width of the rectangle

The volume of gas a balloon can hold varies directly as the cube of its radius. imagine a balloon with a radius of 3 inches can hold 81 cubic inches of gas. how many cubic inches of gas must be released to reduce the radius down to 2 inches?