How do you write 2.1 as a whole number?

Answer 1

The only ways to write 2.1 as a whole number change its value and are to:

1. Multiply it by a multiple of 10, eg 2.1 x 10 = 21
2. Approximate it by truncating (deleting) the decimal part: 2.1 → 2
3. Approximate it by rounding it:
   1. To the nearest whole number: 2.1 → 2
   2. To the nearest 3: 2.1 → 3
   3. To the nearest 4: 2.1 → 4
   4. To the nearest 5 or greater: 2.1 → 0

Or to put it another way 2.1 is a decimal number that, in this case, can be represented using fractions (either an improper fraction of 21/10 or a mixed number of 21/10) with whole numbers for the numerator and denominator.