6.43 rounded to the nearest tenth is 6.40
The place after the decimal is the tenths place. We rely on the value of the hundredths place to know whether we round it up or we round it down to the nearest tenths. If the number is 5 and above, we round it up. If the number is below 5, we round it down.
3 is below 5 therefore from 6.43 we round it down to 6.40
