HOW TO FIND THE MISSING DIGIT

Examples 1-8 : Find the missing digit.

Example 1 :

Solution :

From the above calculation, the missing digit is 7.

Example 2 :

Solution :

From the above calculation, the missing digit is 3.

Example 3 :

Solution :

From the above calculation, the missing digit is 9.

Example 4 :

Solution :

From the above calculation, the missing digit is 7.

Example 5 :

Solution :

From the above calculation, the missing digit is 8.

Example 6 :

Solution :

From the above calculation, the missing digit is 8.

Example 7 :

Solution :

From the above calculation, the missing digit is 4.

Example 8 :

Solution :

From the above calculation, the missing digit is 1.

Example 9 :

In the product given below, if 2y is a two digit number, find the value of y.

(2y)(12) = 348

Solution :

(2y)(12) = 348 ----(1)

The digit in ones place of 288 is 8.

In 2y and 12, the product of the digits in once place (y and 2) will produce the digit in ones place of the resulting number 288, that is 8.

So, the value of y can be 4 or 9.

Because,

4 x 2 = 8

9 x 2 = 18

Substitute y = 4 in (1).

(24)(12) = 288

(y = 4 doesn't work)

Substitute y = 9 in (1).

(29)(12) = 348

(y = 9 works)

Therefore the value of y is 9.

Example 10 :

If the following number is evenly divisible by 3, find the least possible value of K such that K > 0.

3K4591

Solution :

According to divisibility rule, if a number is evenly divisible by 3, the digits in the number will add up to a multiple of 3.

Add the digits in the given number 3K4591.

3 + K + 4 + 5 + 9 + 1 = 22 + K

If k = 2,

22 + k = 24 ----> multiple of 3

If k = 5,

22 + k = 27 ----> multiple of 3

If k = 8,

22 + k = 30 ----> multiple of 3

Therefore, the least possible value of k is 2.

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