Rigireshoni yemutsetse: mapeya a x na y
Parigireshoni, mutsetse mumwe neumwe une x ne y. Dzvanyai 
, 
, kuti muite rigireshoni yemutsetse. Poyindi 2, 5 inouya kaviri: 2, 
, 5, , 2, 
. Ipapo 12, , 24, . Poyindi 21, 40 inouya katatu: 21, , 40, , 3, . Ipapo 15, , 25, . Iyo 
inovhara tafura: 0..