Let us take a look at all the measures (of time, length, surface, and volume) involved in 1 Kings 6-7, describing the construction of Solomon's Temple :
1 Kings 6:1 In the four hundred and eightieth1 year after (the Exodus), in the fourth year of Solomon, in the second month.
1 The Septuagint has four hundred and fortieth.
1 Kings 6:2 The length thereof was threescore cubits, and the breadth thereof twenty cubits, and the height thereof thirty cubits.
1 Kings 6:3 Twenty cubits was the length thereof; and ten cubits was the breadth thereof.
1 Kings 6:6 The nethermost chamber was five cubits broad, and the middle was six cubits broad, and the third was seven cubits broad.
1 Kings 6:10 Chambers, five cubits high.
1 Kings 6:16 He built twenty cubits on the sides of the house.
1 Kings 6:17 The house, that is, the temple before it, was forty cubits long.
1 Kings 6:20 Twenty cubits in length, and twenty cubits in breadth, and twenty cubits in the height thereof.
1 Kings 6:23 Two cherubims of olive tree, each ten cubits high.
1 Kings 6:24 Five cubits was the one wing of the cherub, and five cubits the other wing of the cherub: from the uttermost part of the one wing unto the uttermost part of the other were ten cubits.
1 Kings 6:25 The other cherub was ten cubits.
1 Kings 6:26 The height of the one cherub was ten cubits, and so was it of the other cherub.
1 Kings 6:31 Doors of olive tree: the lintel and side posts were a fifth part of the wall.
1 Kings 6:33 The door of the temple posts of olive tree, a fourth part of the wall.
1 Kings 6:37 In the fourth year, in the (second) month.
1 Kings 6:38 In the eleventh year, in the eighth month, was the house finished. So was he seven years in building it.
1 Kings 7:1 Solomon was building his own house thirteen years.
1 Kings 7:2 The length thereof was an hundred cubits, and the breadth thereof fifty cubits, and the height thereof thirty cubits.
1 Kings 7:6 The length thereof was fifty cubits, and the breadth thereof thirty cubits.
1 Kings 7:10 Stones of ten cubits, and stones of eight cubits.
1 Kings 7:15 Two pillars of brass, of eighteen cubits high apiece: and a line of twelve cubits did compass either of them about.
1 Kings 7:19 The chapiters that were upon the top of the pillars, four cubits.
1 Kings 7:23 Ten cubits from the one brim to the other: his height was five cubits: and a line of thirty cubits did compass it round about.
1 Kings 7:26 It was an hand breadth thick: it contained two thousand baths.
1 Kings 7:27 Four cubits was the length of one base, and four cubits the breadth thereof, and three cubits the height of it.
1 Kings 7:31 The mouth of it within the chapiter and above was a cubit: but the mouth thereof was round after the work of the base, a cubit and an half.
1 Kings 7:32 The height of a wheel was a cubit and half a cubit.
1 Kings 7:35 In the top of the base was there a round compass of half a cubit high.
1 Kings 7:38 One laver contained forty baths: and every laver was four cubits.
We notice that :
An expression of the form thirty-one and a half cubits makes therefore little sense within the given context.
The above observations still hold, even if we were to take all numeric expressions (not necessarily related to measure) from the aforementioned two chapters into account, with the small caveat that the first would have to be amended to read exact multiples of five.