(1 + c)/(r + e + c). The money multiplier (also called the credit multiplier or the deposit multiplier) is a measure of the extent to which the creation of money in the banking system causes the growth in the money supply to exceed growth in the monetary base.
A buzzing light switch could mean the fixture is wearing out, causing an arc of electricity behind the wall plate. If this is the case, the potential for an electrical fire may exist.
It that doesn't work, connect the 2 wires form the switch together with a wire nut and turn the power on. If the light stays on constantly, the problem is the switch. Replace it and you should be good to go. If the light flickers, then the fixture is probably bad.