Final answer:
To round to the nearest tenth, look at the digit in the hundredth place and apply the rounding rules.
Step-by-step explanation:
To round to the nearest tenth, we look at the digit in the hundredth place. If it is 5 or greater, we round up, and if it is less than 5, we round down. For example, 142 cm rounded to the nearest tenth would be 140 cm because the digit in the hundredth place is 2, which is less than 5. Similarly, 6.3 cm rounded to the nearest tenth would be 6.3 cm because the digit in the hundredth place is 0, which is less than 5. The same process is applied to round 13.5 cm and 18.9 cm to the nearest tenth.