Rollup merge of #35860 - matthew-piziak:mul-example, r=GuillaumeGomez
Rollup merge of #35860 - matthew-piziak:mul-example, r=GuillaumeGomez

replace `Mul` example with something more evocative of multiplication

I may have gone a bit overboard on this one. Numbers are fun.

graydon/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,GBGamer/rust,aidancully/rust,GBGamer/rust,GBGamer/rust,GBGamer/rust,aidancully/rust,GBGamer/rust,graydon/rust,GBGamer/rust,GBGamer/rust,GBGamer/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust