HOW TO FIND THE UNIT DIGIT IN THE PRODUCT EXPRESSION

Example 1 :

What is the unit digit in the product

(684 x 759 x 413 x 676) ?

Solution :

Unit digit of 684 is 4.

Unit digit of 759 is 9.

Unit digit of 413 is 3.

Unit digit of 676 is 6.

The product of unit digits :

4 x 9 x 3 x 6

By grouping the first and second term, we get

4 x 9  =  36

By grouping the third and fourth term, we get

3 x 6  =  18

The product of unit digits of the above two groups :

6 x 8  =  48

The unit digit of 48 is '8'.

The unit digit of the product 4 x 9 x 3 x 6 is 8.

Therefore, the unit digit of the given product expression is 8.

Example 2 :

The unit digit in the product

784 x 618 x 917 x 463 is 

Solution :

Unit digit of 784 is 4.

Unit digit of 618 is 8.

Unit digit of 917 is 7.

Unit digit of 463 is 3.

The product of unit digits is

4 x 8 x 7 x 3

By grouping the first and second term, we get

4 x 8  =  32.

By grouping the third and fourth term. we get

7 x 3  =  21.

The product of unit digits of the above two groups :

2 x 1  =  2

The unit digit of the product (4 x 8 x 7 x 3) is 2.

Therefore, the unit digit of the given product expression is 2.

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