Since (256,337)=1, by Lemma 12 we know that 256x≡ 179(mod337) has integer solutions. Since 337=256+81,256=81× 3+13,81=13×6+3,13=4×3+1, we get 1=13 4×3=13−4×(81−13×6)=25×13−4×81= 25×(256−81×3)−4×81=25×256−79×81⇒ 25×256−79×(337−256)=104×256−79×337. Therefore, we have
104×256≡1(mod337)
By 256x≡179(mod337) and Lemma 5, we have
104×256x≡104×179(mod337)
Since 104×179=55×337+81, we get
104×179≡81(mod337)
From (32) to (34), we get x≡81(mod337).