4.35 rounded to the nearest whole number equals 4.
46.49 can be rounded to 46.5, for its 9 is larger than 4.
35.9 is already at the nearest tenth, so it does not change.
The mystery number is 155. When rounded to the nearest hundred, it rounds to 200. The sum of its digits is 1+5+5=11 which is greater than 10, so we must adjust the digit in the hundreds place. When rounded to the nearest ten, 155 rounds to 160, which has digits summing up to 1+6+0=7.
19.872 rounded up to the nearest hundredth is 19.87 correctly .
It is 4 when rounded to the nearest whole number because .09 is less than .5
Assuming you want to round it to a whole number, you look at the first digit after the decimal point. As it is a 9 and any digit from 5 to 9 causes a rounding up, then the figure is rounded up from 7.9 to 8.