Réponses

2013-05-06T00:21:38+02:00
101*99=(100+1)(100-1)=100^2-1^2=10000-1=9999

971*1029=(1000-29)(1000+29)=1000^2-(30-1)^2=1000000-900+60-1=999100+60-1=999159

57*43=(50+7)(50-7)=50^2-7^2=2500-49=2451