what is 6.42 rounded to 1 decimal place?

The nearest two 1 decimal  numbers of 6.42 are 6.4 and 6.3

To round off this observe the digit at hundredth place i.e., 2

2 is less than 5 so it round down to 6.4

It's 6.4

6.4

Source : Calculator Soup, rounding number calculator