Kenichi's scores 100 marks! (忍法ヤギのコピーでござるの巻) is episode 689 of the 1981 anime.Kenichi gets a hundred in the maths exam - but a goat eats the paper. Will Hattori save the paper before it's too late?
Kenichi is over the moon when Mr Koike presents him with his maths question paper - which has a hundred marks on it! After showing it to Yumeko and her gaggle of girlfriends, Kenichi runs home - only for Kemumaki to snatch the paper from him. Kenichi opens his bag and reveals his many other copies. Kemumaki sends them flying, but Kenichi just hopes they'll reach his family and friends, before showing a shellshocked Kemumaki his last copy.
Coming home, Kenichi hears that Mr and Mrs Mitsuba have gone out for the day, so he shows his copy to Hattori and the gang. They are disbelieving at first, but Hattori agrees to take a photo of him. However, while they pose in the park, a goat hired by Kemumaki and Kagechiyo gobbles the paper up. Horrified, Kenichi faints.
Later on, Hattori brings Kemumaki, Kenichi, Yumeko, Shishimaru, Shinzo and Kagechiyo to the garden. Then he milks the goat - and the milk has a hundred on its top! As the others look on in surprise, the goat suddenly empties its bowels - and the remainder is shaped like a hundred as well! Hattori then throws a piece of paper into the goat's mouth, which it spits out immediately. Kenichi picks the paper up and jumps for joy - it's his answer sheet! As he celebrates with Yumeko and Shishimaru, Hattori whispers to Shinzo what really happened: he had Mr Koike copy his paper, before putting a sticky paper ball into the goat's mouth. As the goat spat it out, Shishimaru fetched the copy and did away with the ball. As the others celebrate, Kemumaki and Kagechiyo bemoan the failure of their plans.