This document presents an investigation into idiomatic expressions containing numbers in English and Vietnamese. It explores the role of numbers in creating meanings of idioms in both languages. The study examines types of numerical idioms based on their meanings, the frequency of numbers appearing in idioms, and the connotative meanings implied by numbers. The investigation aims to compare the contribution of numbers to idiom meanings in English and Vietnamese. It employs quantitative and qualitative methods to analyze data collected from various sources.