What is front-end estimation

Front-end estimation is a particular way of rounding numbers to estimate sums and differences.

To use front- end estimation, add or subtract only the numbers in the greatest place value. Then add the decimals rounded to the nearest tenth.

Step-by-step explanation:

In front end estimation we are going to replace the original number with a number that is close by but only has one non zero digit. Examples: {20, 300, -50, 1,000, 80,000}. For example take the number 32, the choices to replace it with are 30 or 40 (they both have only one non-zero digit).

the answer is b. 60. each interior angle in 120, so the exterior angle must be 60 in order to add up to 180

step-by-step explanation: