Question

Cate numerele naturale de forma abcd exista , care sa indeplineasca conditia : a + b + c = d unde d mai mic sau egal cu 4 ?

Answer 1

a,b,c,d cifre,a≠0
pt d=0⇒a+b+c=0⇒a=b=c=0 nu convine
pt d=1⇒a+b+c=1⇒a=1,b=c=0 (a nu poatr fi 0)⇒1001
pt d=2⇒a+b+c =2⇒a=1,b=1,c=0 sau a=1,b=0, c=1 sau a=2,b=c=0⇒1102,1012,2002
pt d=3⇒a+b+c=3⇒a=b=c=1saua=1,b=0,c=2saua=2,b=0,c=1saua=1,b=2,c=0sau a=3,b=c=0⇒1113,1023,2013,1203,3003
idem cu 4