In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.

[EX Q]: Black women giving birth have a four to _ higher rate of mortality than white women do.
[EX A]: one

[EX Q]: Corals are _ fold.
[EX A]: two

[EX Q]: Many computers currently use _ digits to record the year.
[EX A]:
two