Question

What is 76.78 rounded to the nearest whole number?

Answer 1

Lets look at the number. 76.78. In each of the different place holders the number is higher than 5. Lets do some examples. 74 rounded to the nearest whole number is going to be 70. 76 rounded to the whole number will be 80. The .78 in your question also contributes. 

Answer: 80

Answer 2

When rounding to the "nearest whole number" you will need to either round up or down.
If its within 1 2 3 or 4 you round down, so if our number was 73, the nearest whole number would be 70.
Our question here consist of 76.78. 
Well just by looking at the first part of the number, 76, we already know that we are rounding up. so in doing this, I was able to get 80 because when 5 6 7 8 or 9 you round up.