20. Quyidagi sonlarning mavjud yoki mavjud emasligini muhokama qiling. Agar mavjud bo‘lsa, ularning qiymatini yozing: a) eng katta musbat butun son; b) eng kichik musbat butun son; c) eng katta manfiy butun son; d) eng kichik manfiy butun son.

a) Eng katta musbat butun son mavjud emas: istalgan musbat butun sondan kattaroq yana bir butun sonni yozish mumkin.

b) Eng kichik musbat butun son mavjud va u 1.

c) Eng katta manfiy butun son mavjud va u −1.

d) Eng kichik manfiy butun son mavjud emas: istalgan manfiy butun sondan ham kichikroq butun son bor.