Let's say that the number we are looking for is called 'x'.
3 * x = 40
3x = 40
To solve for 'x', we will need to divide both sides by 3.
3x/3 = 40/3
[tex]x = \boxed{\bf{\frac{40}{3} = 13\frac{1}{3}}}[/tex]
40/3 or 13 1/3 can be multiplied by 3 to get 40.