Among various interaction modes in VR/AR, microgestures have distinct advantages over controllers by reducing fatigue and improving the efficiency. In this paper, we proposed a microgesture set that utilizes the number of fingers as input instructions for magnification adjustment in VR environments. To evaluate the effectiveness of the proposed microgestures, a series of tasks have been designed in three scenes. The results revealed a significant improvement in completion time and subjective measures compared to the performance of controller. These findings offer valuable insights for future gesture design, contributing to the development of more efficient and user-friendly interaction techniques in VR.