*In this post, we will see how to multiply two numbers which end in 5 and the other digits of the two numbers when added gives rise to an even number. For example, the following will make it more clearer.*

**1) 15 * 55 (Both the numbers end in 5, and the sum of other digits of both the numbers gives rise to an even number, that is, 1 + 5 = 6)**

**2) 35 * 75 (Ends in 5 & (3 + 7) = 10)**

**3) 45 * 85 (Ends in 5 & (4 + 8) = 12)**

**4) 65 * 125 (Ends in 5 & (6 + 12) = 18)**

**5) 95 * 155 (Ends in 5 & (9 + 15) = 24)**

**6) 135 * 195 (Ends in 5 & (13 + 19) = 32)**

*Now, we will take one example and see the steps to follow in order to find the product of those numbers. Let us remember this method works fine for any digit numbers and not restrained only to 2 digit numbers.*

**1) 15 * 55**

*a) There are two parts for the answer. They are LHS & RHS.*

*b) The final answer looks like LHS/RHS.*

*c) The RHS is always 25. So, RHS = 25.*

*d) To get the value of the LHS, first multiply the other digits of the number.*

*That is, 1 * 5 = 5.*

*e) Next, find half of the sum of the other digits of the numbers.*

*That is, ((1+5)/2) = (6/2) = 3.*

*f) Add the numbers obtained in steps (d) & (e).*

*That is, 5 + 3 = 8.*

*g) The final answer is LHS/RHS = 8/25 = 825*

**Solved Examples**

*2) 35 * 75 = ((3*7)+((3+7)/2))/25 = (21+(10/2))/25 = (21+5)/25 = 26/25 = 2625*

3) 45 * 85 = ((4*8)+((4+8)/2))/25 = (32+(12/2))/25 = (32+6)/25 = 38/25 = 3825

4) 65 * 125 = ((6*12)+((6+12)/2))/25 = (72+(18/2))/25 = (72+9)/25 = 81/25 = 8125

5) 95 * 155 = ((9*15)+((9+15)/2))/25 = (135+(24/2))/25 = (135+12)/25 = 14725

6) 135 * 195 = ((13*19)+((13+19)/2))/25 = (247+(32/2))/25 = (247+16)/25 = 26325

3) 45 * 85 = ((4*8)+((4+8)/2))/25 = (32+(12/2))/25 = (32+6)/25 = 38/25 = 3825

4) 65 * 125 = ((6*12)+((6+12)/2))/25 = (72+(18/2))/25 = (72+9)/25 = 81/25 = 8125

5) 95 * 155 = ((9*15)+((9+15)/2))/25 = (135+(24/2))/25 = (135+12)/25 = 14725

6) 135 * 195 = ((13*19)+((13+19)/2))/25 = (247+(32/2))/25 = (247+16)/25 = 26325

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