Early Spanish missionaries recorded the number-words of Old Tagalog before these had been significantly influenced by the Spanish language. Old Tagalog numbers were constructed with an unusually complex form of over-counting, with four main rules for naming ten sets of ten for each power of ten. The Filipinos were literate and numerate long before the Spanish arrived in 1521. Centuries earlier, the Filipinos had borrowed scripts from India that contained numerals, and an Indic script called baybayin was used to write Old Tagalog. However, the Filipinos did not use the Indic numerals, instead writing out the Old Tagalog numbers in baybayin as pronounceable words. Most systems of numerical notations accumulate, forming new numbers by adding to a lower bundle (as VI in Roman numerals adds I to V). A few numeral systems back-count, forming new numbers by subtracting from a higher bundle (as IV in Roman numerals subtracts I from V). No known system of numerical notations represents over-counting. Ignoring the available Indic numerals suggests that Old Tagalog numbers were written out phonetically because this method was better at representing their structural logic.