Question

If the unit digit in the product $(459\times 46\times 25\times 28@\times 484)$ is $2$, the digit in place of @ is :

• A. $3$
• B. $5$
• C. $7$
• D. $8$

Answer 1

The correct option is C $7$

A number is made up from digits in the numeral system is called Unit's Digit. We often use the decimal system in which we use $10$ digits, In writing the any number, many digits are used, even repeatation of digits. when we write any number using the digits, the last digit ( from right side ) in that number is called unit digit. For example in the number $48750$, here $"0"$ is called unit digit.

Now, the product of unit digits in the given product $459\times 46\times 25\times 28@\times 484$ is shown below:

$9\times 6\times 5\times @\times 4=216\times @$

Now, it is given that the unit digit is $2$, so, to obtain $2$ in the unit's place, let $@=7$ (because $6\times 7=42$), then we have:

$216\times @=216\times 7=1512$ where $2$ is the unit digit.

Hence, the digit place of $@$ is $7$.