What is $7.351$ round to one decimal place?

Hint: We first need to check if the digit next to the precision is greater than or equal to or less than $5$ . Since the second decimal number is $5$ . So, we need to increment the first decimal number. The rounded off number becomes $7.400$ .

Complete step-by-step solution:
Before starting the problem, we need to know what rounding off means. Rounding off a number basically means to approximate the number to a certain extent. We generally round off a number to some defined precision, like the tenth, hundred, one decimal place and so on. All the digits after the precision are dropped, that is they are occupied by the number zero. There is a thumb rule associated with it. It is that if the digit next to the precision is greater than or equal to $5$ , then the precision place digit is incremented by one. But, if it is less than $5$ , then no change is done to the precision place number. For example, if the numbers are $1253$ and $1255$ , and we need to round it off to the tenth, then the numbers become $1250,1260$ .
For the given number $7.351$ , the second decimal number is $5$ . So, we need to increment the first decimal number.
Thus, we can conclude that $7.351$ round to one decimal place is $7.400$.

Note: We must be careful enough to check the digit next to the precision place. Students make a very common mistake which is that they do not increment if the digit next to it is equal to $5$ . This is wrong.