# Check WordPress versions from root
find . -path "*wp-includes/version.php" | xargs grep -o "\$wp_version = '\([^']*\)" | cut -d "'" -f2

Example:

4.1.24

# Or this…
find . -path "*wp-includes/version.php" | xargs grep "\$wp_version ="

Example:

$wp_version = ‘4.1.24’;