Karatsuba's method makes it possible to estimate Kloosterman's sums, the number of summands in which does not exceed m ε {\displaystyle m^{\varepsilon }} , and in some cases even exp ⁡ { ( ln ⁡ m ) 2 / 3 + ε } {\displaystyle \exp\{(\ln m)^{2/3+\varepsilon }\}} , where ε > 0 {\displaystyle \varepsilon >0} is an arbitrarily small fixed number.
Karacubos metodas leidžia įvertinti Klostermano sumas, kuriose dėmenų skaičius neviršija m ε {\displaystyle m^{\varepsilon }} , o kai kuriais atvejais net exp ⁡ { ( ln ⁡ m ) 2 / 3 + ε } {\displaystyle \exp\{(\ln m)^{2/3+\varepsilon }\}} , čia ε > 0 {\displaystyle \varepsilon >0} yra bet koks mažas fiksuotas skaičius.