The Ideal Body Weight for Children ages 1-10 (Leffler Formula) is used to estimate the weight of children in circumstances (such as emergencies) when actual weight cannot be measured.
The Math/Science
The following formula is used for children between 1 and 10:
`m=2a_y+10`
where:
Wikipedia (https://en.wikipedia.org/wiki/Human_body_weight#Estimation_in_children)