2) 237 = a*100 + b*10 +c = 2*100+3*10+7
a*b*c = 2 * 3 * 7 = 42
3)abc=cba;
100a+10b+c=100c+10b+a;
⇒100a=100c⇒a=c;
⇒10b=10b⇒b=b⇒adevarat;⇒b={0,1,2,3,4,5,6,7,8,9}⇒10 variante;
⇒c=a⇒a=c;
⇒a,c=[1,2,3,4,5,6,7,8,9]⇒9 variante fiecare;
⇒9·10=90 numere care indeplinesc conditiile problemei
4) 9999 - 8 345 = 1 654 (de numere sunt pina la cel mai mare nr de 4 cifre)
1 654 : 2 = 827 numere pare