In line with the rising demand for smarter solutions and embedded systems, Microelectromechanical systems (MEMS) have gained increasing importance for the Internet of Things (IoT) applications, most notably for mobile wearable devices. This is driven by their simplicity, sensitivity, reliability, and low power consumption. Hence, they are being explored for ultra-low-power computing machines. However, the realization of energy-efficient complex logic functions and the cascadability of MEMS resonator-based computing devices have introduced new challenges, such as using the outputs of logic units as inputs into others, which is necessary for realistic implementations. This study demonstrates a complex logic function (half-adder) and fundamental logic gates (XOR and AND) based on selective modes activation. The concept is based on the activation and deactivation of the vibration modes of an F-shaped coupled resonators. The proposed approach requires power for actuation only, and this results in significant improvement in energy efficiency because it does not need DC-based frequency modulations. It shows promising low consumed energy in femtojoules per logic operations. The proposed scheme provides prospects for cascadable MEMS resonator logic devices since it enables both the logic inputs and outputs to be in the same AC signal mode at the same frequency.