Explanation:
1. We have to divide 4200 by a number which is a multiple of 10.
Let us assume that the number is 20, which is a multiple of 10.
Now, after division the quotient will be .
2. We have to check whether the quotient is multiple of 10 or not.
Here, the quotient is 210 which is a multiple of 10.
Hence, the required number which is a multiple of 10 is 20.