The correct option is A 800
Given numbers 42 and 23.
Consider number 44, ones digit is 4 which is less than 5.
Hence, ones digit will be replaced with 0 and tens digit will remain the same.
So, 44 will be rounded off to 40.
Similarly consider number 23, ones digit is 3 which is less than 5.
Hence, ones digit will be replaced with 0 and tens digit will remain the same.
So, 23 will be rounded off to 20.
The estimated numbers are 40 and 20.
Estimated product
=40×20=800