Brad is in Year 6. He has learnt the correct column names for
decimal numbers, but attempts to write too many digits into a column.
Just as 12000 has three zeros after the 12 to indicate thousands,
Brad thinks that the number of zeros after the decimal point indicates
the name of the decimal. So 0.12 is 12 tenths (as there is no zero
after the point) while 0.012 is 12 hundredths (as there is one zero
after the point). In effect, he is squeezing the number 12 into
a single column. Column Overflow thinking is one of the longer-is-larger