In the simple Keynesian model, the multiplier (k) is given by the formula k = 1 / (1 - MPC), where MPC is the Marginal Propensity to Consume. MPC is the proportion of an increase in income that is spent on consumption. - If MPC is high, (1 - MPC) is low, and the multiplier (1 / (1 - MPC)) is high. - If MPC is low, (1 - MPC) is high, and the multiplier (1 / (1 - MPC)) is low. Therefore, multipliers will be lower with a low marginal propensity to consume.