A synthetic-speech calculator includes a keyboard consisting of digit keys and function keys and, if desired, or more mode selectors, a desired number of registers for storing numerical information entered by the depression of selected ones of the digit keys, a read-only-memory for storing a large number of digital codes as sound quantizing information, counter means for specifying the address of the memory so as to take a specific digital code out of the memory, a digital-to-analogue converter for convering the specific digital code taken out of the memory into an audible sound signal, and a loud speaker driven by the audible sound signal and producing an audible sound. There are further provided means for producing audible sounds indicative of not only numerical information but also its associated conditional information having a particular meaning with respect to that numerical information, for example, position information, index information, tabulation information, etc. Those numerical information and conditional information is derived in different audible forms. Specifically, a first sound indicates the most significant digit of the data, a second sound (monotone peep) separates the first sound from a third sound representing the data.