小数点

From 小数 (shōsū, “decimal”) +‎ 点 (ten, “point, dot”).

小(しょう)数(すう)点(てん) • (shōsūten) 

1. decimal point, radix point

A decimal point itself is pronounced as てん (ten, literally “dot”). For example, 9.58 is pronounced as きゅうてんごーはち (kyū ten gō hachi, literally “nine point five eight”) and 19.19 is pronounced as じゅうきゅうてんいちきゅう (jū-kyū ten ichi kyū, literally “ten-nine point one nine”).

In vertical writing, [[.]] is replaced with ・. For example, 9.98 is written as 9・98 in vertical writhing. However its pronunciation does not change.

There is some exception. てん (ten, literally “dot”) is sometimes replaced with コンマ (konma, literally “comma”), especially when integer part is zero. For example, 0.31 is normally pronounced as れいてんさんいち (rei ten san ichi, literally “zero point three one”) or exceptionally pronounced as れいコンマさんいち (rei konma san ichi, literally “zero comma three one”). In this case, integer part is sometimes omitted to pronounce. 0.3 can be read as コンマさん (konma san, literally “comma three”).

• 浮(ふ)動(どう)小(しょう)数点(すうてん) (fudō shōsūten, “floating point representation”)
• 浮(ふ)動(どう)小(しょう)数点(すうてん)演算(えんざん)機(き)構(こう) (fudō shōsūten enzan kikō, “floating-point arithmetic unit”)