The task is to generate the correct answer for a given math problem.

Input: Consider Input: Problem: find the least number must be subtracted from 105829 so that remaining no . is divisible by 21 ?

Output: 10

Input: Consider Input: Problem: a train 360 m long runs with a speed of 45 km / hr . what time will it take to pass a platform of 150 m long ?

Output: 40.8 sec

Input: Consider Input: Problem: 9 men working 8 hours per day dig 30 m deep . how many extra men should be put to dig to a depth of 50 m working 6 hours per day ?
Output: 11