1.21 rounded to the nearest whole number

1.2

1 is the whole number and to round you look one place over, in this case the number one over to the left if 2. If the number to the left is 5 or more you “raise the score” making the number your rounded go up one. If the number is 4 or less, you “let it rest” meaning the number stays the same. Once you round, you drop every number behind the number you used to round. So instead or 1.21 it’s 1.2