Add: 23 + 35 = 2 · 53 · 5 + 3 · 35 · 3 = 1015 + 915 = 10 + 915 = 1915. The common denominator you can calculate as the least common multiple of the both denominators - LCM(3, 5) = 15. Calculator performsbasic and advanced operations with fractions, integers, decimals and mixed numbers.