Jesus mentions children in various contexts throughout the Gospels. It's difficult to give an exact number because it depends on how you define a "mention" and which translations you consult. However, we can identify some key passages and themes:
* Blessing the children: (Matthew 19:13-15, Mark 10:13-16, Luke 18:15-17). These are parallel passages where people bring children to Jesus for him to touch and bless them. Jesus rebukes the disciples for trying to stop them, saying, "Let the little children come to me and do not hinder them, for to such belongs the kingdom of heaven" (or similar wording). This is one of the most famous and significant mentions of children.
* Using a child as an example: (Matthew 18:1-5, Mark 9:36-37, Luke 9:46-48). The disciples argue about who is the greatest in the kingdom of heaven. Jesus calls a child to him and says that unless they become like children, they will not enter the kingdom of heaven. He also says that whoever welcomes a child in his name welcomes him.
* Warning against causing children to sin: (Matthew 18:6-7, Mark 9:42, Luke 17:1-2). Jesus warns that it would be better to have a millstone tied around one's neck and be drowned in the sea than to cause one of these little ones who believe in him to sin.
* Prophecies involving children: Jesus also references the prophecies in the Old Testament about the slaughter of the innocents.
* Healing a child: There are accounts of Jesus healing children, such as the daughter of Jairus, or the demon possessed child, depending on whether you are counting them as mentions.
Overall, considering the various passages and contexts, Jesus mentions children or makes direct reference to their characteristics *at least* 10-15 times in the Gospels.