Final answer:
After rounding each number to the nearest whole number, you subtract 5 from 21, resulting in an estimate of 16 for 21.2−4.8.
Step-by-step explanation:
To estimate 21.2 - 4.8 to the nearest whole number, we can round each number to the nearest whole number and then subtract. 21.2 rounded to the nearest whole number is 21, and 4.8 rounded to the nearest whole number is 5. The number 21.2 rounds down to 21 because the digit after the decimal point is less than 5. The number 4.8 rounds up to 5 because the digit after the decimal point is 8, which is 5 or higher. Now, subtract the rounded numbers: 21 − 5 = 16. The nearest whole number estimate for 21.2−4.8 is therefore 16.