Facebook is blocked in China, not Russia. However, there are plenty of Chinese MAUs when factoring VPNs and those who travel abroad. Basically, you can subtract

Facebook is blocked in China, not Russia. However, there are plenty of Chinese MAUs when factoring VPNs and those who travel abroad. Basically, you can subtract the total Chinese population from the world population and assume you've properly discounted the global population to account for the few other countries where it's banned and factored in those who travel or connect via VPN (Iran, North Korea, etc).