Computers use binary internally, but they display decimal to users.
Tips
usage
Almost always appears as 十进制 (shíjìnzhì, "base-10 system") rather than 十进 alone. The bare form 十进 mostly turns up in technical compounds: 十进数 (decimal number), 十进位 (decimal place).
memory
进 here is the math sense "to carry over to the next place value" — when you reach 十 (ten) you 进 (advance) to a new column. That's exactly what "base-10" means.
